TWI749073B - Device for combining light beams interacting with adjacent pixels of light modulator - Google Patents

Abstract

The present invention relates to a device for combining light beams interacting with adjacent pixels of a light modulator. The invention also relates to a beam combining device and a spatial light modulator for complex value modulation. The present invention also relates to a light beam combination device and an optical device of a polarization sensitive element, wherein the polarization sensitive element can generate complex value modulation of the light field through the phase modulation light modulator and the beam combiner. Not sensitive to changes. In addition, this document also deals with different configurations of reflective working light modulators.

Description

Device for combining light beams interacting with adjacent pixels of light modulator

The present invention relates to a device for combining light beams interacting with adjacent pixels of a light modulator. The invention also relates to a beam combination device and a spatial light modulator for complex value modulation of light. The present invention also relates to a light beam combination device and an optical device of a polarization sensitive element, wherein the polarization sensitive element can generate complex value modulation of light through the phase modulation light modulator and the beam combiner, and this complex value modulation changes the incident direction of the light source Not sensitive.

The device as described above is particularly suitable for holographic displays for three-dimensional reconstruction of objects and/or scenes. For example, WO 2006/066919 A1 or other documents proposed by the applicant have descriptions of such displays.

DE 10 2009 044 910 A1 and WO 2010/149583 A1 describe the different constructions of beam combination devices that combine two phase pixels of a spatial light modulator into a complex-valued pixel. This beam combination device is referred to below as Beam combiner. The two pixels are adjacent to each other. In this document, the so-called adjacent pixels of the light modulator specifically refer to pixels that are directly adjacent to each other in space, where the pixels may be adjacent to each other in horizontal, vertical, or other directions (for example, diagonals). The light from two pixels of a pixel group will have different polarizations after passing through the SLM. This phenomenon is caused by structured retardation wave plates. Lights of different polarizations will pass through the beam combiner in different paths, so the beams are superimposed or combined at the exit of the beam combiner. In this document, the so-called beam combination means that after the combination, the combined beams have a substantially same spreading direction in a spatial overlapping area.

Figure 1 (and similar Figure 8) of WO 2010/149583 A1 shows a structured aperture aperture AP of the prior art and a polarization-selective layer PS for light diffusion related to polarity, such as a calcite layer. For the sake of simplification, this figure only schematically depicts the geometric shape of light diffusion, and does not take diffraction into consideration.

The incident light is decomposed into a first polarized light and a second polarized light. For example, the first polarized light is a linear light that passes through the layer and is directed to the first pixel of the spatial light modulator pixel (SLMPIX), and the second polarized light is a shot. The linear light directed to the second pixel of the SLM PIX, for example, the second polarized light is perpendicular to the first polarized light, and is also linear. For easy identification, the dotted line represents one kind of polarized light, and the dotted line represents another kind of polarized light. For a liquid crystal-based phase modulation SLM, for example, an SLM that only modulates the phase of a specific input polarized light can additionally provide a structured retardation wave plate WP at the exit of the polarization sensitive layer. The effect of this is that before the light (for example, the light directed to the second pixel) enters the SLM PIX, the polarization of the light will be deflected, so that only one kind of polarized light will pass through the SLM. If it is a reflective SLM, the light will be reflected back along the same path, and the light of the two pixels of a pixel group will be superimposed again at the position of the aperture opening.

Figure 2 shows the situation without an aperture diaphragm. For easy identification, the light incident on the position before the aperture diaphragm is drawn in another shade of gray. Light from both polarization directions will reach every pixel. After passing through the SLM PIX, light will reflect back from each pixel in two directions. On the return journey, the light from pixel 1 and pixel 2 will be superimposed in the desired way. However, the light of pixel 2 will also overlap with the light of pixel 3, which is an undesirable phenomenon. In this case, the practicability of this beam combining device (beam combiner) is not high.

The purpose of the present invention is to provide a beam combination device and further improve it to avoid the above-mentioned problems.

The device of the present invention is used to combine light beams interacting with adjacent pixels of a light modulator. The light modulator has a plurality of pixels, and each two adjacent pixels constitute a giant pixel. For a giant pixel, the beam splitter is structured and designed to split the incident beam into a first partial beam and a second partial beam. The first partial beam travels in the direction of the first pixel of the giant pixel, and the second partial beam Propagate in the direction of the second pixel of the megapixel. It is preferable to split the beam into a first partial beam and a second partial beam of substantially the same intensity. A first structured beam influencing element is arranged between the beam splitter and the light modulator, and its function is to enable the first partial beam to be affected in a different manner from the second partial beam. After interacting with the pixels of the giant pixels, the first partial light beam and the second partial light beam pass through the second structured light beam influencing element, whose function is to make the first partial light beam different from the second partial light beam (preferably the opposite way) affected. A beam combiner is provided, and its function is to combine the first partial beam and the second partial beam together. A beam selector is arranged between the light modulator and the first or second structured beam influencing element, and its function is to select (for example, absorb or reflect) the first partial beam and/or the second partial beam that do not belong to the giant pixel. The light modulator of this device is preferably capable of transmitting the incident light/two partial beams, or the incident light passes through the light modulator only once. Hereinafter, such a device is referred to as a transmission working device.

The device of the present invention is used to combine light beams interacting with adjacent pixels of a light modulator. The light modulator has a plurality of pixels, and each two adjacent pixels constitute a giant pixel. For a giant pixel, the beam splitter is structured and designed to split the incident beam into a first partial beam and a second partial beam. The first partial beam travels in the direction of the first pixel of the giant pixel, and the second partial beam Propagate in the direction of the second pixel of the megapixel. It is preferable to split the beam into a first partial beam and a second partial beam of substantially the same intensity. There is a structured structure between the beam splitter and the light modulator The beam influencing element has the function of enabling the first partial beam to be influenced in a different manner from the second partial beam. After interacting with the pixels of the giant pixels, the first partial light beam and the second partial light beam pass through the second structured light beam influencing element, whose function is to make the first partial light beam different from the second partial light beam (preferably the opposite way) affected. There is a reflective medium, whose function is to reflect part of the light beam. After interacting with the pixels of the light modulator, the first part of the light beam and/or the second part of the light beam pass through the structured beam influencing element and pass through the beam splitter again to combine the first part of the light beam and the second part of the light beam together again . A beam selector is arranged between the light modulator and the structured beam influencing element, the function of which is to select the first part of the light beam and/or the second part of the light beam that does not belong to the giant pixel. The incident light/two partial light beams preferably interact with the light modulator of the device in a reflective manner. The first method is to make two partial light beams pass through the light modulator twice, for example, the first incident light passes through a liquid crystal layer of a light modulator, then is reflected on a reflective medium, and then passes through the liquid crystal layer a second time. Liquid crystal on silicon (LCoS) is an example of such a light modulator. Another way is that the pixels of the light modulator can contain reflective media, so that the two partial light beams will interact with a reflective pixel respectively. Micro Electro Mechanical System (MEMS) is an example of such a light modulator. Hereinafter, this kind of device is called a reflection working device.

The present invention first recognizes that in order to avoid the diffraction effect that may cause interference on the structured aperture, the device of the present invention does not need to use such a structured aperture, and it can still prevent the split beam from being inappropriate The method is inadvertently affected by neighboring megapixels. Therefore, the combined effect of the beam selector and a structured beam influencing element is equivalent to the function of the structured aperture, which is no longer necessary, that is, the first partial beam and/or the second partial beam that do not belong to the giant pixel can be selected. However, its mode of action is not that the structured aperture does not let any light beam enter the beam combination device at its light transmission point as in the prior art. The device of the present invention allows all incident light beams to enter the device of the present invention, so that the beams are combined, and then (to a certain extent, first inside the device) pass through the beam selector and The combination of structured beam influencing elements selects the first partial beam and/or the second partial beam that do not belong to the giant pixels. Since the device of the present invention does not need to use a structured aperture, another advantage is that the structured aperture does not need to be aligned with the pixel position of the light modulator.

The following first presents various advantageous embodiments and improved methods of the present invention in a general manner, and then uses specific examples to further illustrate the advantageous embodiments and improved methods of the present invention in the description part of the drawings.

In the transmission working device, the beam splitter and the beam combiner can be identical birefringent uniaxial optical components. In this case, the beam splitter and the beam combiner may be made of the same material and/or have the same optical axis. In particular, the alignment of the optical axis of the beam splitter is the same as the alignment of the optical axis of the beam combiner. The alignment of the optical axes of the two birefringent uniaxial optical components can be set so that the angle (θ) between the two components and the interface is the same as the angle between the ordinary and extraordinary partial light beams. The purpose of using birefringent uniaxial optical components is to combine polarized light beams and/or partial light beams with each other. In particular, the incident beam is linearly or circularly polarized, in which the polarization direction of the incident beam is aligned in a prescribed direction, for example, the beam splitter splits the incident beam into a first partial beam and a second partial beam (basically both have The same intensity), where the first part of the light beam propagates in the direction of the first pixel of the giant pixel, and the second part of the light beam propagates in the direction of the second pixel of the giant pixel.

In the reflective work device, the beam splitter that is passed twice by the two partial beams can be a birefringent uniaxial optical member. In this case, the beam splitter has a dual function. The first function is to split the incident beam into the first part of the beam and the second part of the beam, and the second function is to recombine the first part of the beam and the second part of the beam. Together.

Another possibility is that the beam splitter and/or beam combiner is not a birefringent uniaxial optical component, but at least one is a volume grating or at least one is a polarization grating. But in this situation In this case, if the device of the present invention is to be applied to light of different wavelengths, the divergence characteristics of the volume grating or polarization grating used must be corrected. In this case, at least one corresponding grating can also be provided for light of different wavelengths. Therefore, if light beams of different wavelengths are to be used, it is better to apply beam splitters and/or beam combiners made of birefringent optical components to the device of the present invention.

A very advantageous way is that the structured beam influencing element has a spatial structure, which can regionally realize the function of a retarder, wherein the retarder has a λ/2 wave plate and/or a λ/4 wave plate. The structured beam influencing element may additionally have a spatial structure that does not cause regional changes to the optical characteristics of the partial beam.

The spatial structuring of the structured beam influencing element is preferably matched with the spatial structure of the pixel of the light modulator. For example, imagine that the structure of the structured beam influencing element is vertically projected on the structure of the pixel of the light modulator. This kind of projection is basically Will produce exactly equal areas. It should be noted here that the above considerations are all related to the optical characteristics of the components of the beam combination device of the present invention, rather than related to the control circuit of the light modulator, although the components of the circuit may also interact with light.

If it is a reflective work device, the pixels of the light modulator can reflect themselves, such as MEMs. Another possibility is to install a mirror behind the light-transmitting pixels of the light modulator.

A particularly advantageous way is that the beam splitter, beam combiner, first and/or second structured beam influencing elements are designed and arranged in such a way that the optical path of the first partial beam and the optical path of the second partial beam are substantially The point symmetry is based on the midpoint between the first pixel and the second pixel of the giant pixel. To be correct, the point symmetry based on the midpoint between the first pixel and the second pixel of the giant pixel is located on a plane. This plane is the optical path of the first partial beam and the second partial beam belonging to the second partial beam. The plane where the optical path lies. From the perspective of the entire megapixel, there is a symmetry based on the middle section of two adjacent pixels. Especially the design and configuration of transmission working devices, beam splitters and/or structured beam influencing elements The arrangement is such that the optical path of the first partial light beam and the optical path of the second partial light beam are basically symmetrical with respect to the beam splitting point and/or the beam combining point. A particularly advantageous advantage of these improved methods of the beam combination device of the present invention is that even if the incident direction of the incident beam is different from a prescribed normal incident direction, the partial beams are still correctly split and combined. In other words, these improved methods of the beam combination device of the present invention are not sensitive to the incident direction. Other advantageous embodiments of the present invention will be mentioned elsewhere in the text.

A particularly advantageous way is that the beam selector has a polarizer, or the beam selector is composed of a polarizer. The polarizer is preferably a non-spatially structured element. The configuration of the polarizer allows it to form the first partial beam and/or the second partial beam that are not part of the giant pixels.

A particularly advantageous way is to provide a beam superimposing element whose function is to enable the first partial beam and the second partial beam to be interfered. The beam superimposing element can also be a polarizer, whose function is to make the combined maximum amplitude of the two partial beams to be superimposed basically have the same amplitude value, so as to realize the effective phase modulation of the giant pixels.

If the light modulator contains liquid crystal LC, since the alignment direction of the liquid crystal can be changed through electronic control modulation, in order to avoid electrolysis during electronic control modulation, in principle, a cycle of voltage reversal can be realized. Usually, a frame inversion method, a column inversion method, or a pixel inversion method can be used to specifically implement a voltage inversion. The frame inversion method first controls all pixels with the same sign voltage, and then controls all pixels with the sign reverse voltage. The column inversion method is usually to control the pixels of adjacent rows or adjacent columns of the light modulator with voltages with different signs. For example, firstly, voltages with positive signs are used to control even-numbered rows, and voltages with negative signs are used to control odd-numbered rows. Then all the pixels are controlled with the sign-inverted voltage. The pixel inversion method usually uses positive and negative voltages arranged in a checkerboard arrangement.

A particularly advantageous way is to control the pixels of the megapixels with voltages of the same sign. In order to do so, if the column inversion method is used, every two adjacent pixels of the giant pixel can be arranged in the same row or column to be inverted. Another feasible way is to replace the column inversion mode with the double column inversion mode. The operation mode is to use the voltage with the same sign to control two adjacent rows or columns, and then control the two adjacent rows or columns with the sign inversion voltage. Of rows or columns. The first pixel of the macro pixel may be located in the first row or the first column, and the second pixel of the macro pixel may be located in the second row or the second column. Another possibility is to use a pixel inversion method, which involves an electrical inversion, whose function is to invert the two pixels of a giant pixel in the same way. If it is a frame-type inversion method, the pixels of all the giant pixels of the light modulator are controlled by voltages of the same number.

The beam splitter, if necessary, a beam combiner, at least one structured beam influencing element, and/or a beam selector are basically arranged parallel to each other with a space on one side or the other. A particularly advantageous way is to make the beam splitter, the beam combiner, if necessary, at least one structured beam influencing element, and/or the beam selector close to each other, or fixed to each other (sandwich structure) ). Doing so can produce a compact and strong sandwich structure, for example, this structure can be optimized for temperature changes without the need to drastically change the optical properties. For example, an adhesive can be used to fix various components together. In particular, in order to realize the symmetry of the components of the device of the present invention mentioned earlier, it is preferable to use the same adhesive to adhere different layers together.

Specifically, the incident light beam may have a linear polarization or a circular polarization. After alignment or adjustment, the light beam can be split into a first partial beam and a second partial beam, and then combined together.

If it is a reflective working device, a flat lighting device (similar to WO 2010/149583 A1). This flat lighting device can be a lighting device similar to that described in WO 2010/149583 A1. The lighting device may have a flat light conductor and an output unit, wherein the light emitted by the light conductor is output through the output unit and can be deflected to the direction of the light modulator. The light reflected on the reflective medium can pass through the illuminating device in a substantially undeflected manner, and then propagate outward through the beam combiner, but the premise is that the polarization device of the corresponding beam must be adjusted appropriately.

If the light modulator contains liquid crystal, and its liquid crystal can be rotated out of plane, such as the liquid crystal of electronically controlled birefringence (ECB) mode, the incident light beam can be linearly polarized, and the structured light beam influence element can have a regional λ/2 The function of the wave plate.

The light modulator may contain liquid crystals, and the liquid crystals rotate in-plane. This design method often appears in hybrid alignment liquid crystal (HAN-LC) mode, continuous in-plane rotation (CIPR) mode, or smectic liquid crystal mode. In these modes, the rotation of liquid crystal molecules in the plane of the electric field is dominant. In contrast, the out-of-plane rotation is extremely insignificant. In addition, the light modulator may also contain a liquid crystal having a cholesteric phase, and the optical axis of the liquid crystal has an in-plane rotation in the electric field (lateral spiral structure mode). In the various situations mentioned above, the incident light beam may be linearly polarized, wherein the structured light beam influencing element has the function of a regional λ/4 wave plate. The structured beam influencing element can change the polarization, thus allowing circularly polarized light to enter the light modulator. For example, it is possible to generate regional right circularly polarized light and regional left circularly polarized light through the structured light beam influencing element.

In other words, the objective of the present invention can also be achieved through a beam combiner with a structured retardation wave plate. The structured retardation wave plate has an SLM side, that is, when viewed from the structured retardation wave plate to the SLM, at least one polarizer is also provided.

1000: Beam combiner SLM (BC-SLM)

1001: Pure phase SLM

1002: structured half-wave layer (sHWP)

1003: Polarization selection element

1004: linear polarizer

AP: Structured aperture aperture

BM: black mask

BP: Backplane

DE: Dielectric mirror

DG: glass substrate

E: Electrode

FL: headlight lighting device

FWP: full wave plate

HAN: Hybrid Exchange

HWP: Half-wave layer

I: Insulation layer

IPS: In-plane switching

Iso: Isotropic layer

ITO: indium tin oxide

LC: liquid crystal

LE: Linear electrode

nsQWP: Unstructured quarter-wave layer

P: Polarizer

PI: Polyimide

PIX: pixel

Pol: Polarizer

PS: Polarization selective layer

PSC: Polarization selection element

Px: pixel gap

QWP: 1/4 wave layer

rP: reflective polarizer

sHWP: structured half-wave layer

SLM: Spatial Light Modulator

sHWP1: The first structured half-wave layer

sHWP2: The second structured half-wave layer

sP: structured polarizer

sQWP: structured quarter-wave layer

srP: structured reflective polarizer

tE: Plane electrode

tP: Transmissive polarizer

WGP: Wire grid polarizer

WP: Delay wave plate

It can be seen from the above description that there are different possibilities to implement the theory of the present invention in an advantageous manner, and to develop different improvements. In the following, on the one hand, the attached patent scope of the present invention, which refers to the scope of independent patent applications, is taken as a reference for further explanation, and on the other hand, advantageous embodiments of the present invention will be explained in conjunction with the drawings. In addition to explaining the advantageous embodiments of the present invention in conjunction with the drawings, general advantageous configurations and improvements will also be explained. The following figures are drawn in a schematic way, among which: Figure 1 and Figure 2: A beam combiner belonging to the prior art.

Figures 3a and 3b: The first embodiment of the device for combining light beams interacting with adjacent pixels of a reflective working light modulator according to the present invention.

Figure 4: The second embodiment of the device of the present invention for combining light beams interacting with adjacent pixels of a transmission working light modulator.

Figure 5: The upper image shows the phase produced by the phase difference function between two phase values, and the lower image shows the amplitude and intensity of the phase difference function.

Figure 6: The upper figure shows the adjustment contrast of the phase difference function, and the lower figure shows the intensity difference of the phase difference function.

Figure 7: A beam combiner belonging to the prior art. In Figure 7a on the left, the beams to be combined from adjacent pixels are basically incident on the light modulator. In Figure 7b on the right, adjacent The light beam to be combined of the pixels is incident on the light modulator in a direction at an angle with the vertical line of the surface.

Figures 8a and 8b: A beam combiner of the present invention. In Figure 8a above, the beams to be combined between adjacent pixels are basically incident on the light modulator. In Figure 8b below, The light beams to be combined from adjacent pixels are incident on the light modulator in a direction at an angle with the vertical line of the surface.

Figure 9: A beam combiner similar to Figures 8a and 8b of the present invention, wherein the light modulator in Figure 9 is based on an in-plane liquid crystal mode.

How to apply electrodes and mirrors in the in-plane liquid crystal mode controlled by the in-plane electric field.

Figure 10: A device with a beam combiner belonging to the prior art is schematically shown in a schematic way. The upper right of the figure is a side view, and the lower right is a three-dimensional view.

Figure 11: Shows the intensity results of a 2D image achieved by the device in Figure 10 on the light modulator.

Figure 12: The bottom right shows schematically the configuration of two adjacent pixels of the light modulator, and the phase values Φ ₁ and Φ ₂ are written into these two pixels.

Figure 13: Graphically shows the effect of phase error on the intensity modulation of a 2D image.

Figure 14: Shows the propagation of an ordinary beam and an extraordinary beam in a uniaxial birefringent medium (refractive index n _o and n _e ), in which both sides of the birefringent medium are surrounded by the same isotropic medium. The refractive index of an isotropic medium is n.

Figure 15: Shows the calculation results of the optical path changes of the ordinary beam and the extraordinary beam in the birefringent medium. The light does not enter the birefringent medium perpendicularly, but is inclined at a small angle α (between 0 and 0.5° Between) into the birefringent medium.

Figure 16: shows another consideration, that is, taking into account the total optical path difference in the uniaxial birefringent medium and the surrounding isotropic medium.

Figure 17: Shows the calculation of the absolute phase difference △Φ with the incident angle α and angle δ. The thickness of the calcite wave plate is about 756 microns.

Figure 18: Shows the relative phase difference and the change of △Φ (the arc of the circle is 2π).

Figure 19: Shows the "black box mode" to analyze the impact of the change in △Φ related to the angle change.

Figure 20: Shows the relationship between the tolerable angle change △Φ and the pixel gap Px of the light modulator.

Figure 21: Shows a device for combining light beams that belongs to the prior art.

Figure 22: Shows a configuration of the prior art, which has a light modulator based on phase modulation of a liquid crystal LC operating in an "out-of-plane" liquid crystal mode.

Figure 23: shows in a schematic way the configuration of such a device belonging to the prior art LCoS.

Figures 24 and 25: Show how to modify the electrode E of the LCoS so that it can use the in-plane electric field to perform active disconnection.

Figures 26 and 27: Show how electrodes and mirrors are used in an in-plane liquid crystal mode controlled by an in-plane electric field.

Figure 28: A schematic diagram of a phase modulation device that uses the liquid crystal mode of the prior art for in-plane modulation.

Figure 29: Shows a way to achieve phase modulation based on an in-plane liquid crystal mode, where the in-plane liquid crystal mode is like the device in Figure 28 of an LCoS with electrodes as in Figure 27 and a dielectric mirror DE.

Figure 30: A schematic representation of a further phase modulation device using the liquid crystal mode of the prior art for in-plane modulation.

Figure 31: Shows a way to achieve phase modulation based on an in-plane liquid crystal mode, where the in-plane liquid crystal mode is like the device in Figure 30 of an LCoS with electrodes as shown in Figure 27 and a dielectric mirror DE.

Figure 32: The device shown schematically is for in-plane modulated liquid crystal mode to produce a different polarization for adjacent pixels.

Figures 33 and 34: Each shows a device with a structured polarizer sP.

Figure 35: Shows another possibility of phase modulation by out-of-plane modulation LC and the different polarizations of the light emitted by the light modulator from adjacent pixels.

Figure 36: Shows a detailed view of the configuration of Figure 35.

Figure 37: Shows a device similar to that shown in Figure 36.

Figure 38: Shows another device for out-of-plane modulation in the LC layer.

Figure 39: A detailed view showing the same configuration.

Figure 40: Shows another possible configuration. On the back of the configuration, an unstructured quarter-wave layer is provided between the LC layer of the light modulator and the mirror.

Figure 41: The device shown has two quarter-wave layers.

Figure 42: Shows a headlight illuminator that illuminates the light modulator.

Figure 43: Shows the detailed structure of the configuration of Figure 42.

Figure 44: Shows a more advantageous device than Figures 42 and 43.

Figure 45: Shows a detailed view of the configuration of Figure 44.

Figure 46: Shows the LC mode with the backside polarizer applied to out-of-plane modulation.

Figure 47: Shows the detailed structure of the configuration of Figure 46.

Figure 48: The device shown has a headlight illuminator that couples light and a glass substrate.

Figure 49: The device shown has a beam combiner composed of a plurality of optically birefringent uniaxial components.

It is advantageous to use a polarizer with an SLM that itself requires polarized light, such as an SLM based on liquid crystal (LC). Of course, it is not limited to only using this SLM, but other types of SLM can also be used.

A very advantageous way is to use a polarizer with a reflective SLM with small pixels, such as liquid crystal on silicon (LCoS), but it is not limited to only using this SLM.

The function of the polarizer and its equivalence with the aperture diaphragm will be explained below.

Figures 3a and 3b show the beam combination device of the present invention, which has a polarizer Pol for reflective SLMPIX.

Figure 3a shows the forward path of the light: the polarization selective layer PS propagating with the polarization selective light causes the light of the two polarization directions to reach the two pixels first. The light then passes through the structured retardation wave plate WP. On the forward path, one of the two polarization directions is filtered by the polarizer Pol.

Assuming geometric light propagation, the effect of this filtering will be equivalent to the effect of the prior art structured retardation wave plate as shown in Figure 1. Because the polarizer only lets light from a position within the aperture pass. However, in actual situations where interference diffraction on the aperture is taken into consideration, it is more advantageous to use a device equipped with a polarizer. This is especially true for small pixels.

Figure 3b shows the return journey of the light after passing through the reflective SLM. Only the pixel group that I want (that is, pixel 1 and pixel 2) is superimposed, and pixel 2 and pixel 3 will not be superimposed. When using a reflective SLM, the polarizer can selectively reflect on its own, and the polarizer is placed on the back of the SLM.

Figure 4 shows an embodiment of a transmissive SLM that allows inversion. This SLM does not have an aperture diaphragm, but has a polarizer Pol placed at the entrance of the SLM PIX, where the polarizer Pol is located between the two polarization selective layers PS . In addition, there are two retardation wave plates WP.

Of course, there are other possible configurations, for example, SLM modulates the phase of the circulating light. For this reason, an additional retardation wave plate is required in the device. Therefore, the scope of the present invention is not limited to the arrangement shown in Figs. 3 and 4.

Hereinafter, a device for combining light beams interacting with adjacent pixels of a light modulator will be described from another point of view. This device is combined with the previously described solution on the one hand, but can also be separated from the previously described solution on the other hand. This other point of view relates to the sensitivity to changes in the angle of incidence of light on the beam combination device.

The light-influencing element configured in an asymmetrical manner (superimposing two phase pixels) makes the superposition of two adjacent pixels based on double-beam interference very sensitive to the extremely small changes in the optical path caused by the light modulator-sandwich structure. The total intensity I _R =A _R ² =(U _R ．U _R ^* ), which is produced by the coherent superposition of _{two waves U R} = U ₁ + U _2:

I_R

1。以下將這個狀態稱為標準狀態。如果兩個部分波中的一個部分波經歷一個額外的相位移π，這會導致所顯示的灰值圖反轉，也就是說產生一對比反轉。根據第6圖，調節對比(Michelson contrast)介於原本的明亮像素及黑暗像素之間，也就是C_M=-1。在校準的標準狀態下，調節對比=1。實際情況與這個理想狀態僅容許有一很小的偏差，以確保對比損失不造成干擾。作為可以接受但並非確實定義的邊界，在接下來的說明中，假定C_M的最小容許值為C_M=0,924，這在相對相位誤差為π/8=0.3927弧度(rad)時就已經發生。 Among them, A ₁ and A ₂ represent the amplitude of partial waves, and △Φ represents the relative phase difference of two partial waves (partial beams). If the two amplitudes are equal, that is, A ₁ =A ₂ =0,5, according to Figure 5, the total intensity depends on the cosine of the relative phase difference △Φ, that is, when △Φ=0, it is structured interference (That is, the maximum intensity), when △Φ=π, it is destructuring interference (that is, the minimum intensity). Now suppose that the spatial light modulator (SLM)-sandwich structure is calibrated, so that the two partial waves φ ₁ and φ _{2 that affect the relative phase difference △Φ=φ 2-} φ ₁ correctly show the intensity reached by the SLM output terminal. Value 0

I _R

1. Hereinafter, this state is referred to as the standard state. If one of the two partial waves experiences an additional phase shift π, this will cause the displayed gray value map to invert, that is to say, a contrast inversion occurs. According to Figure 6, the Michelson contrast is between the original bright pixels and dark pixels, that is, C _M = -1. In the standard state of calibration, the adjustment contrast=1. Only a small deviation between the actual situation and this ideal state is allowed to ensure that the contrast loss does not cause interference. As can be accepted but does not define the boundaries, in the following description, it is assumed that the minimum allowable value C _M C _M = 0,924, in which the relative phase error has occurred when the π / 8 = 0.3927 radian (rad).

But an important thing for holographic displays is to be able to display the amplitude and phase correctly, otherwise the reconstruction quality of the scene will be significantly reduced. An incorrectly displayed holographic amplitude value will result in a gray value that is too low or cannot be displayed in the reconstruction. It can be clearly seen from Figure 6 that the gray value is equivalent to 0.5 times the intensity, and it will be the most sensitive response to small changes in the phase difference, because in this range, the intensity of the phase difference (phase 2-phase 1) The partial differential is the largest.

The following will take WO 2010/149588 A1 as an example. This patent discloses a beam combining device. Please also refer to Figure 7 of this application for this part. This type of device uses polarization sensitive elements (single-axis crystals) to combine two partial beams modulated by SLM into a composite beam. This assumes that the relative phase difference between the two partial beams caused by the different light wavelengths in the polarization sensitive element (uniaxial crystal) has been calibrated to the standard state, so the two waves are "in phase", that is to say, there is no relative phase difference. . Therefore, the phase value is known, and this phase value must be written into the phase sub-pixel to be superimposed to display the desired giant pixel amplitude value.

For example, the standard state is calibrated under normal incidence (Figure 7(a)). The thermal expansion or mechanical load of the thermal display or the lighting device of the display may cause a small relative flip between the incident wave and the SLM-sandwich structure. This will result in an extra optical path (optical path difference) in one of the two partial beams to be combined, that is, an additional phase △Φ=OPD*2π/λ. This additional phase is determined by the incident angle α of the light, _{the distance (pitch) of the pixels p x} to be superimposed, and the wavelength of the light:

In order to facilitate understanding, it is necessary to recognize that the optical path difference or the major change in the wavelength of the light is not caused by the polarization sensitive element (see Figure 15), but by the geometric reversal. As shown in Figure 7(b), the path of the surrounding medium has a decisive influence on this. By definition, all incident beams and outgoing beams are parallel to each other (the characteristic of a plane-parallel wave plate, surrounded by the same medium), and all lie on the same plane (the characteristic of a uniaxial crystal whose optical axis lies on the incident plane). Therefore, the polarization sensor can be regarded as a "black box" (see Figure 19). The polarization sensor has been calibrated once to make the two partial beams "in phase". Therefore, the calibrated standard state is completely It may be a state where the incident angle is not exactly 0. The important thing is that only this state will have the correct phase superimposition. All relative deviations from the standard state will cause the problems described above, thus causing the shortcomings of the solutions proposed according to the prior art.

The following will explain this issue more clearly with a numerical example. According to the previously derived standard, the minimum adjustment contrast C _M =0,924, the maximum allowable relative phase error △Φ=π/8=0.3927 radians (rad), the maximum allowable deviation of the incident angle of light is α, according to the above formula α=arcsin {λ/(16p _x )}. When the wavelength λ=532nm, the pixel pitch is 50μm, the allowable change in the angle of incidence is 0.038°; the pixel pitch is 100μm, the allowable change in the angle of incidence is 0.019° (see Figure 20). It is technically difficult or even impossible for a display system under mechanical load and thermal load to control the error within such a small allowable error. The so-called pixel pitch here refers to the average pixel size or average pixel distance, especially the distance in the direction where two pixels are combined into one giant pixel, such as horizontal pixel pitch/pixel distance, that is, two horizontally adjacent pixels Combined into a giant pixel.

In addition, WO 2010/149583 A1 describes a device consisting of a reflective light modulator (SLM), a beam combiner, and a headlight. In this device, the light passes through the beam combiner twice, that is, from the headlight to the SLM through the beam combiner, and then passes through the beam combiner again on the return journey after being reflected on the back of the SLM. In this process, the structured aperture has divided the incident light into two partial beams according to the polarity of the incident light in the forward pass. The first partial beam is deflected to the first pixel of the pixel group, and the second partial beam is deflected to the pixel group. The second pixel. After two SLM pixels are modulated, the two partial beams are again superimposed at the output end of the beam combiner during the return journey. This device has very little tolerance for the geometric reversal of the beam relative to the standard state.

Therefore, the purpose of the present invention is to provide a beam combination device and a spatial light modulator for complex-valued modulation of light, and these two devices are very insensitive to changes in the incident angle of light and/or deviations from the standard state.

In order to achieve the above objective, the method of the present invention is to make the entire optical path in the spatial light modulator (SLM)-sandwich structure symmetrical, that is, to make the possible flips uniformly act on the two partial beams to be superimposed And thus cancel each other out. The general design principle according to the present invention is described as follows. The symmetry rule forms a symmetrical interferometer type with symmetrical interferometer branches (reflection: Michelson, transmission: Mach-Zehnder). Its main functions include beam splitting, independent beam modulation and beam recombination. For this reason, the (mainly phase-modulated) SLM should be embedded between the polarization sensitive elements, and the optical medium separated by the two partial beams in space is arranged in the direction of light propagation in a symmetrical manner, so it is different for different incidents. In terms of angle, the sum of the optical path lengths of the two partial beams OPL ₁ and the optical wavelength of _{OPL 2 is fixed.} Taking the component part of the fully complex SLM based on pure phase modulation LC-SLM as an example, the LC-SLM (which can be out-of-plane or in-plane LC rotation) is embedded between the polarization suppliers (which can be HWP or QWP), The LC-SLM and the polarization supplier are embedded between the polarization selective element (PSC) (PSC1 and PSC2, respectively). The interference generator (which can be a linear polarizer) is located beside the PSC2.

The device for combining light beams interacting with adjacent pixels of a light modulator of the present invention includes a light modulator having a plurality of pixels and a beam splitting member, wherein the beam splitting member is preferably a single-axis dual Refraction member and a beam combining member, wherein the beam combining member is preferably a uniaxial birefringent member and a beam superimposing member. The function of the beam splitting component is to split the incident beam into a first partial beam and a second partial beam. The first partial beam propagates to the first pixel of the light modulator, and the second partial beam propagates to the Two pixels, and the first partial light beam and the second partial light beam preferably have the same light intensity; the function of the beam combination component is to combine the first partial light beam and the second partial light beam with the corresponding pixels after the first partial light beam and the second partial light beam interact with the corresponding pixels. The second part of the light beams are combined together. The structure and arrangement of the beam splitting component and the beam combination component are such that the optical path of the first part of the light beam (for example, the optical path based on the polarization characteristic) and the optical path of the second part of the light beam (for example, the optical path based on the polarization characteristic) The point symmetry is basically based on the midpoint between the first pixel and the second pixel.

The above solution will be further described with an embodiment below. In this embodiment, a birefringent material is used as the polarization sensitive element. The basic principle of the above-mentioned solution (that is, the symmetrical optical paths traveling separately) can also be applied to other types of polarization-sensitive optical elements, such as volume gratings (volume Bragg gratings) or polarization gratings. However, if necessary, other types of retarders (structured or unstructured retarders) must be used according to the type of polarization-sensitive optical element and the entrance polarization required by the SLM (especially the phase-modulated SLM), such as λ/4 wave Plate (Quarter Wave Layer (QWP) for Polarization Grating) or adapt to the order of each layer.

Figures 8a and 8b show an embodiment of the combination of a spatial light modulator and a beam combiner, where the beam combiner contains at least one birefringent medium (uniaxial crystal) as a polarization sensitive element, which functions to combine the light modulator SLM Two phase modulation sub-pixels are combined together. The sub-pixel group composed of two phase modulation sub-pixels constitutes a giant pixel. In order to make the drawing easier to observe, Figures 8a and 8b only show a section of the spatial light modulation device (the actual range of the spatial light modulator in Figures 8a and 8b extends to the left and right) and the two adjacent pixels Part of the light beam, these two adjacent pixels should be superimposed according to the principle of double-beam interference.

The phase modulation light modulator SLM (operating in ECB mode) is set in two structured half-wave layers sHWP1 and sHWP2 and two uniaxial plane parallel crystal waves with the same optical axis orientation. Between slices (see Figures 8a and 8b). First, the first single-axis crystal (single-axis crystal 1) beam splitter splits the beam into two polarized partial beams that are perpendicular to each other, which penetrate the structured HWP to generate the required input polarization for the SLM, and then these two Part of the beams are modulated by SLM, and then the two beams are combined by a second uniaxial crystal (uniaxial crystal 2). Then the two partial beams are interfered by linear polarizers (which have an automatic compensation function for phase difference changes), and one of the linear polarizers set at an angle of about 45° is located at the exit end of the device. The device composed of uniaxial crystals 1 and 2, SLM and half-wave layer is completely symmetrical on the optical path of the two partial beams separated from each other. Only the aperture diaphragm (black mask) and the linear polarizer at the exit end of the device are not point mirror symmetry to the center of the SLM. The optical axis of the birefringent uniaxial medium enables the angle θ of the interface of the two uniaxial mediums to achieve a constant discrete angle (the angle between the ordinary beam and the extraordinary beam). There are some characteristics in this case. First of all, it is sturdy, due to the inherent automatic compensation. Secondly, there is no need to actively compensate. Finally, the design principle can be transferred to other types of SLM (liquid crystal and non-liquid crystal).

Figure 8a shows the sandwich structure display in the calibration standard state. The linear incident light is polarized at 45° and reaches the first plane-parallel uniaxial crystal wave plate (uniaxial crystal 1). There is an absorption mask or aperture diaphragm on the crystal wave plate, whose function is to cover each second pixel of the SLM to prevent crosstalk. The 45°-polarized light is split on the crystal wave plate, and the vertically polarized light marked with a small dot in the circle is refracted as an ordinary beam according to Snell's law of refraction and the ordinary refractive index of a uniaxial crystal. This example of perpendicular incidence on the interface with the uniaxial crystal means that the ordinary beam will also pass through the uniaxial crystal perpendicularly. The horizontally polarized light marked with a double arrow travels in an extraordinary beam. The direction of the extraordinary beam is produced by the extraordinary refractive index of the uniaxial crystal and the direction of the crystal axis. After being emitted from the first plane-parallel crystal wave plate, the two beams travel in a direction parallel to the input beam again, but with polarizations (s-pole and p-pole) perpendicular to each other. Due to phase The position modulation SLM requires a vertical incoming polarization, so a structured half-wave layer sHWP1 deflects the polarization of the horizontally polarized partial beam by 90°, but the polarization of the vertically polarized partial beam will not be changed by the structured half-wave layer. Therefore, the structured half-wave layer is used as a structured beam influencing element. This structured beam influencing element has a spatial structure, and some areas will not change the optical characteristics of part of the beam. The SLM is completely traversed by vertical polarization. The two partial beams can have a different or pre-specified (desired) phase delay. This phase delay is equivalent to the value that should be represented by each giant pixel (see Figure 12). Then the ordinary beam of the first crystal wave plate is deflected by another structured half-wave layer sHWP2 by 90° to the horizontal polarization, so this beam will propagate as an extraordinary beam in the next second crystal wave plate (uniaxial crystal 2). The extraordinary beam of the first crystal wave plate (uniaxial crystal 1) passes through the first structured half-wave layer sHWP1 that has been previously deflected, and passes through the second structured half-wave layer sHWP2 in such a way that the polarization direction does not change . Therefore, this beam will propagate as an ordinary beam in the second crystal wave plate (uniaxial crystal 2). The two partial light beams are combined again at the exit end of the second crystal wave plate, and again proceed in a manner parallel to the input light beam. To create interference, the two beams then pass through a 45° linear polarizer located at the rear. The two-beam interference through two phase-modulated sub-pixels can adjust the amplitude of a giant pixel. The phase value of the giant pixels is achieved through the relative phase difference between the single giant pixels of the SLM. This principle is called "dual-phase holographic display", see Figure 12.

Next, in conjunction with Figure 8b, the method of operation of the solution proposed by the present invention is explained, in which the input beam is deflected by an angle α, so that it is irradiated on the SLM at an angle different from the calibration standard state. Part of the light beam passes through the first crystal wave plate in the form of ordinary and extraordinary beams, and then emerges from the crystal wave plate in a manner parallel to the incident beam. The direction of the ordinary beam is produced according to Snell's law of refraction and the ordinary refractive index of the uniaxial crystal, and the direction of the extraordinary beam is produced by the extraordinary refractive index of the uniaxial crystal and the direction of the crystal axis. Through the reversal of the geometric shape, part of the beam 1 will be on the first crystal wave plate (k=| k |=2π/λ-wavenumber; OPD: optical path difference, where the optical path difference is determined by OPD=δ·sin(α) Calculated, where δ represents the distance between the two partial beams) at the exit end produces an additional relative phase delay △φ ₁ =k. OPD ₁ . The opposite occurs at the entrance end of the crystal wave plate 2. Part of the beam 2 here will produce an additional relative phase delay △φ ₂ =k. OPD ₂ . In the case where all the elements on the separated optical paths are symmetrically arranged, the two optical path differences OPD ₁ and OPD ₂ preferably cancel each other, so Δφ ₂ -Δφ ₁ =0.

In order to highlight the problem, Figures 8a and 8b are drawn as if there is an air layer between the components, and all the components do not seem to have glass substrates. However, the complex modulator designed according to the solution of the present invention can also stack all the components together without an air layer, for example, glue them together and arrange them on a glass substrate. Adjust the optical path OPD ₁ =OPD ₂ suggested principle is also valid in this case, but the premise is that there is a symmetrical optical path. It must be noted here that the same connecting material (such as adhesive) or the same glass material should be used as the substrate. Generally speaking, the surrounding optical media should be arranged symmetrically, so that the sum of the optical path lengths OPL ₁ and OPL ₂ of the two partial beams is fixed for different incident angles.

Other advantageous embodiments and/or features:

●The solution proposed by the present invention can also be applied to SLM based on in-plane liquid crystal modulation, see Figure 9. For example, the HAN-LC mode is an example of an LC mode with in-plane modulation. Another example is CIPR mode. The smectic liquid crystal mode in which the liquid crystal molecules rotate in the plane of the electric field far more than the out-of-plane rotation can also be regarded as the in-plane mode. The cholesteric liquid crystal mode (uniform lateral spiral mode, abbreviated as ULH) can also be regarded as an in-plane mode. The so-called in-plane refers to the direction of rotation of the optical axis of the liquid crystal in the electric field. For example, in the case of ULH, the electric field is The body can also be vertically adjacent to the liquid crystal layer. But for in-plane modulation, since the in-plane mode requires circular input polarization, the order of optical components between polarization selection allocation (PSC1-uniaxial crystal 1) and combination (PSC2-uniaxial crystal 2) should be selected in the following way : Unstructured quarter wave plate, set at an angle of 45° (QWP1); SLM (in-plane liquid crystal mode); unstructured quarter wave plate, set at an angle of -45° (QWP2). It should be noted that in this configuration, in the above-mentioned in-plane liquid crystal mode (HAN, CIPR, smectic, ULH), the signs of the phase shifts of the right circular and left circular polarized light are opposite to each other. But this can be taken into account when calculating or displaying the holographic value, so it will not have any influence on the control of the SLM. The advantage of this is that the quarter wave layer (QWP) used is unstructured.

● maximum angle (angle dispersion) between the ordinary beam uniaxial optical medium and the extraordinary beam by the position of the optical axis of the medium, the direction of vector k ordinary light, and the refractive index n _o, n _e and other factors. For example, using calcite as the optical medium, in the case of normal incident light and using an index with a wavelength of 532nm, the resulting value is θ=48.2°. Due to another symmetry relationship (manufacturing, use), an advantageous way is to set the optical axis at about 45°, which can be achieved by grinding and polishing the crystal wave plate. Although this will require a thicker wave plate to ensure the same beam deviation, it can reduce the risk of alignment errors during installation and manufacturing.

●Other polarization-sensitive optical components can also be used for polarization beam splitting and combination. For example, in addition to polarization sensitivity, there are volume gratings or polarization gratings with a high diffraction rate (preferably 100%). It should be noted that there must be two gratings for each wavelength of each beam splitting element (crystal wave plate 1) and combined element (crystal wave plate 2).

●Another advantage is that, unlike the general simple method, two adjacent parts of the wavefront are caused to interfere with two beams, but the same part of the wavefront is first separated, then modulated, and finally combined Together. Therefore, even if the input wavefront has a small transverse wavefront error, it will not cause an amplitude error in the output wavefront like a simple method. Even if the SLM is not considered to modulate the two wavefront parts separately, the simple method is generally to work according to the principle of transverse Schell interference (the wavefront is superimposed with the same wavefront of the transverse offset), but the method proposed in the present invention is Work according to the principle of Mach-Zehnder interference (first split the wavefront, and then combine) to adjust the arms of the wavefront (that is, make the two partial arms have the same optical path).

Figure 10 schematically shows a prior art device with a beam combiner. The upper right of the figure is a side view, and the lower right is a perspective view.

Figure 10 illustrates the optical structure of the beam combiner SLM (BC-SLM) 1000, in which the stack configuration and the components of the complex-valued beam combiner SLM are arranged in order. The beam of the same linear polarization passes through two pixels of a phase-modulated light modulator (phase-only SLM 1001), and then a structured half-wave layer (sHWP) 1002 changes the polarization of the light from one of the two pixels, but The polarization of the light from the other of the two pixels is not changed. The light from the pixel 1 passes through the polarization selective element 1003 (for example, a birefringent layer) in a straight line (undeflected), and the light from the pixel 2 passes through the polarization sensitive element at an angle. The light rays from the two pixels are irradiated at the same position and parallel to each other at the exit end of the polarization sensor, and are thus combined. In Figure 10, the pure phase SLM 1001 may be an LC-SLM in ECB mode. In addition, the polarization selection element 1003 may be a combined calcite wave plate with different thicknesses.

A linear polarizer 1004 set at +45° or -45° relative to the two polarization directions of the two pixels (for example, the polarizer is 45°, and the polarization directions of the light of the two pixels are 0° and 90°) To emit light, the emission intensity is determined by the relative phase of the two pixels, so the emission intensity can be adjusted through the phase modulation of the SLM. If the light emitted from the pixel and reaches the polarizer With the same phase, the maximum emission is produced. If the phase difference of the light is π, the minimum emission is produced.

With the average phase modulation of two pixels, this device can be used for complex modulation of light. A light modulator with multiple pixel groups generates an amplitude and a phase value for each pixel group.

This can be used for the encoding of holographic 3D scenes. However, for the sake of illustration, an example of displaying a 2D image on the light modulation will also be described below.

Figure 11 shows the intensity results of a 2D image achieved by the device of Figure 10 on the light modulator. The intensity of each pixel of the displayed image is adjusted by the modulation phase difference of the two pixels of the light modulator. At the same time, as described in Figure 10, the light of the two pixels is combined at the exit end of the beam combiner . The contrast of the intensity map displayed by the polarizer fades and the gray value curve gradually becomes flat. A relatively weak gray value can be observed in this image, which is not easy to optimize.

Further test results show that the prior art device shown in Figure 10 is also very sensitive to mechanical stress. For example, through the mechanical connection with the frame where the beam combiner device of Figure 10 is located, the loss of contrast can be further reduced, or even the displayed 2D scene can be reversed.

The bottom right of Figure 12 schematically shows the arrangement of two adjacent pixels of the light modulator, and the phase values Φ ₁ and Φ ₂ are written into these two pixels. The following formula can be used to calculate the amplitude (A) of the giant pixel, that is, the amplitude of the light combined by the beam combiner of the two pixels:

The intensity (I) passing through the polarizer is proportional to the square of this amplitude (A):

The amplitude and intensity of the holographic function (H) modulated according to the phase difference of the two pixels is basically equivalent to two-beam interference.

A(x,y)代表振幅及Φ(x,y)代表相位。在巨像素內的一組相位值如以下所示：

這些方程式摘自公開文獻Hsueh,C.K.& Sawchuk,A.A.；Appl.Opt.,1978，第3874-3883頁。 Therefore, if there is an error ΔΦ between the phase difference of the two pixels, the modulated intensity (I) will be different from the expected value. The double phase of the complex-valued holographic function (H) is as follows:

A(x,y) represents the amplitude and Φ(x,y) represents the phase. A set of phase values in a giant pixel are as follows:

These equations are taken from the open literature Hsueh, CK & Sawchuk, AA; Appl. Opt., 1978, pages 3874-3883.

The following is a known equation for two-beam interference:

Among them, assume that A ₁ =A ₂ =0.5 (standardized).

Figure 5 shows the relationship between amplitude and intensity and △Φ.

The right side of Figure 6 shows the adjustment contrast, which includes the adjustment contrast (C _M ) and the intensity error (Δl).

△I = I _nominal - I _actual

If it can be adjusted to the desired phase value, I _max =1 and I _min =0. However, if there is an error in the phase modulation, I _max will become smaller and I _min will become larger, thus making the contrast smaller.

Figure 13 graphically shows the effect of phase error on the intensity modulation of a 2D image.

The upper left shows an error-free image, where the pixel group of the image point modulates the desired phases Φ ₁ and Φ ₂ .

The result is to add an error △Φ in the phase difference Φ ₁ -Φ ₂ and show the influence on the intensity map.

The error △Φ=π/8 _{reduces the adjustment contrast C M} from 1 to 0.924.

The increased error △Φ will first cause the contrast to become smaller, and if the error continues to increase, it will cause the displayed image to be reversed.

Therefore, it can be determined that the adjustment contrast C _{M is} greater than 0.924 and the maximum tolerable phase error △Φ<=π/8 (0.3927 degrees (rad)). At this error, the displayed image has changed visibly. But these changes are still tolerable subjectively. As mentioned earlier, this tolerable phase error is a subjective criterion. Of course, another tolerable error can also be specified.

Figure 14 displays the ordinary light (o-wave) and the extraordinary beam (e-wave) propagating in a uniaxial birefringent medium (refractive index n _o and ne), wherein both sides of the birefringence medium are the same to each The homogeneous medium surrounds, and the refractive index of this isotropic medium is n.

If the incident light is irradiated on the interface of the birefringent medium at an oblique angle, the light propagation between the isotropic medium and the uniaxial birefringent medium should be taken into consideration.

The light beams (ordinary light beam and extraordinary light beam) emitted from the birefringent medium propagate in a manner parallel to each other but staggered from each other.

The optical path length (OPL) only passes through the wave plate. _{The following equation can be used to calculate the optical path of the ordinary beam OPL 0} and the extraordinary beam between the point O (the point entering the birefringent medium) and the points P'and P” (the points where the two beams leave the birefringent medium) Optical path OPL _e :

and

These equations are taken from the publication Veirae et al., Appl. Opt. 2010, pages 2769-2777. As shown in Figure 14, the input beam and the output beam are parallel to each other (the optical axis is on the incident surface).

Where α represents the incident angle of the incident light beam relative to the normal, that is, the angle at which the incident light beam irradiates the birefringent medium in the isotropic medium. L represents the thickness of the birefringent medium. θ represents the angle of the optical axis of the birefringent medium with respect to its surface. δ represents the angle between the incident surface and the projection of the optical axis on the interface.

Figure 15 shows the calculation results of the optical path changes of the ordinary beam and the extraordinary beam in the birefringent medium. The light does not enter the birefringent medium perpendicularly, but is inclined at a small angle α (between 0 and 0.5° Between) shot into the birefringent medium.

This calculation is carried out for the calcite wave plate used as the beam combiner or beam splitter in the 3rd or 4th scope of the patent application.

In this example, when the optical axis is on the incident plane (δ=0), the surrounding medium is air (n=1). The calcite wave plate has n _o = 1.663145 and n _e = 1.488541. The thickness of the calcite wave plate is approximately 756 microns. The angle between the optical axis and the interface is approximately 48.2°. The wavelength of light is 532. The normal incidence angle α is equal to 0°.

As shown by the calculation results, the optical path OPL _{o of the} ordinary beam will increase as α becomes larger, and the optical path OPL _{e of the} extraordinary beam will decrease as α becomes larger.

When the angle α changes from 0° to 0.5°, the change in _{the optical path difference OPD=OPL 0 -OPL e} between the ordinary beam and the extraordinary beam is 48 nm. This is approximately 0.09λ relative to 532nm. This corresponds to a phase difference of 0.18π.

Since the angle change of 0.5° is already greater than π/8, the change of the optical path in the birefringent layer has already affected the intensity map, but on the other hand, the angle change is still quite small, that is to say, the angle change It cannot be used to explain the test results showing that the device is very sensitive to small adjustment changes, so the effect can be ignored.

Figure 16 shows another consideration, which is the total phase shift, that is, the total optical path difference in the uniaxial birefringent medium and the surrounding isotropic medium. Contrast inversion occurs when the phase shift is π or the OPD is λ/2.

Figure 14 does not calculate the optical path between O and P'or P", but calculates the optical path between O and Q'or Q".

The formula for calculating the total phase difference between the ordinary beam and the extraordinary beam with the angle of incidence α is as follows:

Where α represents the incident angle of the incident light beam relative to the normal, that is, the angle at which the incident light beam illuminates the birefringent medium in the isotropic medium. L represents the thickness of the birefringent medium. θ represents the angle of the optical axis of the birefringent medium with respect to its surface. δ represents the angle between the incident surface and the projection of the optical axis on the interface. refractive index n _o and n _e representative of the birefringent material, the refractive index of around n represents an isotropic material. λ _v represents the wavelength of light. Wherein the optical parameters include the refractive index n _o = 1.663 and n _e = 1.489, and the nominal thickness L = 755.8μm.

Figure 17 shows the calculation of the absolute phase difference (between o-beam and e-beam) △Φ with incident angle α and angle δ, where the thickness of the calcite wave plate is about 756 microns. In this example, the surrounding medium is air (n=1). The calcite wave plate has a refractive index n _o =1.663145 and n _e =1.488541. The angle between the optical axis and the interface is approximately 48.2°. The calculation is performed for the wavelength of light of 532 nm.

In the standard state, that is, α=0° (normal incidence) and δ=0°, the phase difference between the ordinary beam and the extraordinary beam is △Φ=757.7 radians (rad), as shown by the black circle in Figure 17.

For example, when α changes from 0° to 0.5°, δ remains at 0°, and the phase difference ΔΦ becomes larger to 766 radians (rad).

If δ also changes, this will also affect △Φ, and the larger the α, the greater the impact caused by the δ change.

Figure 18 shows the change in △Φ (the arc of the circle is 2π). α=0° (normal incidence) and δ=0°. When α changes but δ remains at 0°, comparing α=0.181° and α=0°, we find that The amount of change in △Φ is π. The change of △Φ has a great influence. It is critical and cannot be ignored. The optical path beyond the uniaxial wave plate is critical.

Figure 19 shows the analysis of the relative phase difference, especially the "black box mode" to analyze the effect of the change of △Φ related to the angle change.

Think of the beam combiner (or in this case passing in the opposite direction, therefore the beam splitter) as a "black box" and only consider the phase shift in the surrounding medium.

In the standard state (that is, vertical incidence), the beam combiner is calibrated, in which one phase pixel of the two phase pixels is compensated by a phase modulation, so that both pixels are "in-plane" pixels (where the amplitude A= 1 Calibration). The beam combiner calibrated in this way will provide the desired amplitude modulation. The relationship between the incident angle α, OPD, and pixel gap Px is shown in the following equation:

The phase inversion occurs when the phase shift is π or the OPD is λ/2. Therefore, the incident angle α can be calculated as follows:

When the phase difference △Φ changes by π, so that the incident angle α changes by 0.181°, the contrast will be reversed. These calculations are performed when the wavelength of the light is 532 nm and the pixel gap (Px) of the light modulator is 84 microns. At this time, the required thickness of the calcite wave plate is 756 microns.

After a device with a light modulator and a beam combiner is calibrated once, the light source is flipped once relative to the birefringent layer, which will cause a contrast inversion. That is to say, the allowable error of this device to the incident light inversion is very small.

Figure 20 shows the relationship between the tolerable angle change ΔΦ and the pixel gap of the light modulator.

The starting point is that the maximum tolerable angle change △Φ _max is π/8 (0.3927rad). From this, a tolerable optical path difference can be obtained

Calculated with wavelength=532:

Pixel gap = 84 microns, and the tolerable Δα is about 0.02°. If the pixel gap becomes smaller, the tolerable Δα will become larger. For example, if the pixel gap = 20 microns, the tolerable Δα is about 0.1°.

In this angular range, the illumination wavefront must remain stable relative to the birefringent layer to avoid undesirable changes in amplitude modulation.

0.022°，其等於1.36弧分(arc min)。 Figure 21 shows a prior art device for combining beams. This is a situation in the BC-SLM of a demonstrator for testing. In this case, the tolerable angle of the incident beam |△α|

0.022°, which is equal to 1.36 arc minutes (arc min).

The methods to avoid or overcome these problems are described below. In the first method, the thermal and mechanical stability of the entire display sandwich structure must be considered, and monitoring and active control will cause an erroneous state, that is, fine-tuning the illumination wavefront can solve this problem. However, the implementation of this solution is difficult and expensive. The second method is to achieve a robust and error-tolerant optical design through the principle of automatic compensation. There is great hope for success with this solution.

Finally, it should be pointed out that the embodiments described above are only used to describe the theory of claiming patent rights, but these embodiments do not constitute any limitation on the scope of the present invention. Those who are familiar with the technology can combine all the above embodiments and/or various features with each other based on the theory disclosed in this document.

In the following, the light modulator will be described from another point of view. The light modulator is arranged in a reflecting device. On the one hand, this viewpoint can be implemented without the viewpoint described above, on the other hand, it can be combined with the viewpoint described above, especially with the beam combiner, and/or with the beam combiner shown in Figure 10-20. The sensitivity of the incident angle changes combined.

The following diagram first describes the liquid crystal modulation configuration in a reflective spatial light modulator (SLM), such as an LCoS. These figures will describe the three configurations of the reflective spatial light modulator (SLM):

(a): A device for phase modulation of a light modulator with liquid crystal mode "in-plane" modulation.

(b): A device for phase modulation of an "in-plane" modulated light modulator with a liquid crystal mode with a maximum rotation angle of 180°.

(c): A device for phase modulation of a light modulator with liquid crystal mode "out-of-plane" modulation.

Figure 22 shows a basic configuration (c) of the prior art, which has a light modulator SLM based on phase modulation of liquid crystal operating in an "out-of-plane" liquid crystal mode (ECB mode in this example). This basic configuration has no beam combiner. The linearly polarized light passes through a liquid crystal layer, is reflected on a mirror, and then passes through the liquid crystal layer of the light modulator SLM from the opposite direction. The input polarization must be parallel to the rubbing direction of the LC. The polarization direction is perpendicular to the rubbing direction Straight, and the phase modulation is zero. In other words, the output polarization is always parallel to the input polarization. In the closed state, the thickness of the liquid crystal layer is d, the birefringence is Δn, and the product of the two is equivalent to a half-wave layer (λ/2 layer). This is equivalent to d*△n=λ/2, and the result of double crossing at the same time is 2*d*△n=λ.

If the direction of the liquid crystal molecules is parallel to the incident polarization direction, the polarization of the light will not be rotated when it passes through the liquid crystal layer twice. But when the liquid crystal layer is energized, the optical path will change, and the reflection Δn will become smaller. The change in the optical path is used for the phase modulation of the light.

Figure 23 schematically shows the configuration of such a device belonging to the prior art LCoS. LCoS has a backplane BP and a pixel matrix. The pixel electrode itself is usually reflective, so the mirror and the electrode are combined in the same layer for control. In addition, LCoS also has a glass substrate DG including indium tin oxide ITO transparent electrode E. LCoS also has an alignment layer for aligning liquid crystal molecules, such as an alignment layer made of polyimide PI, or an alignment layer made of inorganic materials (such as silicon dioxide). In this configuration, the PI rubbing directions of the two PI layers are both equal to 0°.

The disadvantage of applying phase-modulated LCoS to holographic displays is that the switching time of a particular liquid crystal mode is too long, such as the ECB mode, especially the passive disconnection time.

One possible way to improve the switch is to actively perform two switching operations, that is, to switch on with an out-of-plane electric field and to switch off with an in-plane electric field.

Figures 24 and 25 show how to modify the electrodes of the LCoS so that the in-plane electric field can be used to perform active disconnection.

Figure 24 shows how to replace the planar ITO electric field E on the glass substrate DG with a structured electrode LE. The ECB mode LCoS with structured ITO electrodes is used for the electric field in the _{t off response time plane.} However, this is not a preferred setting.

Figure 25 shows that in addition to the glass substrate DG, a planar electrode tE is additionally provided, and an insulating layer I is provided on the planar electrode, and a linear electrode LE is provided on the insulating layer. The linear electrode and the planar ITO electrode E (which are continuous electrodes) are controlled with the same voltage to switch on the out-of-plane electric field, but this voltage is different from the voltage connected to the pixel electrode. In order to perform active disconnection, the linear electrode and the planar ITO electrode (which are strip-shaped electrodes) are controlled with different voltages, thereby forming an electric field distribution including an in-plane portion. This setting is better than the one in Figure 24.

Figures 26 and 27 show how electrodes and mirrors are used in in-plane liquid crystal mode, such as in-plane switching (IPS) or HAN controlled by an in-plane electric field. These liquid crystal modes are usually only used for transmissive displays, not for reflective LCoS. In IPS or HAN, the electrode area is smaller than the pixel area, and the electrode is not equal to the mirror. These liquid crystal modes require additional reflective layers, such as dielectric mirrors or WGP.

Since the modulation of the in-plane electric field of the liquid crystal is carried out between two electrodes, the combination of electrodes and mirrors in a single layer, which is common in LCoS, cannot be applied. Placing a metal mirror layer between the electrodes can cause undesirable short circuits.

Therefore, the suggestion in Figure 26 is to install a dielectric mirror DE above the electrode E. In order to operate with a laser in a holographic display, the dielectric mirror DE can be optimized to produce a large reflection at the wavelength of the laser used.

However, compared to the configuration without the dielectric mirror DE, the layer stack located between the electrode E and the liquid crystal layer will cause the liquid crystal layer of the light modulator SLM when the voltage is the same as that of the electrode E. The intensity of the electric field becomes smaller. It is speculated that the dielectric mirror DE between the electrodes E and LC will affect the fringe field (smoothing). Therefore, it is preferable to arrange the dielectric mirror DE under the electrode.

Therefore, the device shown in Figure 27 has a relatively thick electrode E and a dielectric mirror DE located between the electrodes E, but no dielectric mirror DE is provided above the electrode E. In this way, the desired reflection can be generated on the dielectric mirror DE and the desired in-plane electric field can be achieved in the liquid crystal layer.

Figure 28 schematically shows a liquid crystal mode using the prior art, which is a basic configuration (a), a phase modulation device for in-plane modulation. There is no beam combiner in this configuration. There are first and second sQWPs in this configuration, and this sQWP is necessary on the mirror. Otherwise, the entire phase modulation of the first and second paths is zero. Each QWP can be +45 or -45°. Regardless of 0° or 90° light input, when the output polarization is either case (even if the QWP is structured), the output polarization will be the same as the input polarization. The incident light with linear polarization first passes through an unstructured quarter-wave layer nsQWP, wherein the angle of the optical axis of the unstructured quarter-wave layer nsQWP with respect to the incident polarization direction is 45°. Then the light passes through the liquid crystal layer, where the optical thickness of the liquid crystal layer is equivalent to the thickness of a half-wave layer, and then passes through another unstructured quarter-wave layer nsQWP, where this unstructured quarter-wave layer The optical axis of the layer nsQWP is parallel to the first nsQWP. For example, the two unstructured quarter-wave layers nsQWPs can be achromatic quarter-wave layers QWP. The light is then reflected on a mirror and passes through the layers in reverse order on the return journey. The linearly polarized light emitted through each layer has the same polarization direction as the incident light. Through the control of the liquid crystal layer, the optical axis of the liquid crystal is rotated in the plane. This rotation results in a phase modulation equivalent to twice this rotation angle on both the outgoing and return trips. In this configuration, the phase modulation amounts to 4 times this rotation angle. Therefore, a rotation of +/-45° (+/-π/4) in the plane is sufficient to achieve a phase modulation of +/-π.

Figure 29 shows a way to achieve phase modulation based on the in-plane liquid crystal mode (a), where the in-plane liquid crystal mode is like a LCoS with electrode E and dielectric mirror DE as shown in Figure 27. Figure 28 installation. QWP is located above the electrode and will again affect the fringe field (smoothing). QWP is only provided between the electrodes.

Figure 30 schematically shows a liquid crystal mode using the prior art, which is a basic configuration (b) (only HAN, not IPS), a phase modulation device for in-plane modulation, which is different from Figure 28 installation. There is no beam combiner in this configuration. The incident light with linear polarization first passes through a quarter-wave layer QWP, wherein the angle of the optical axis of the quarter-wave layer QWP with respect to the incident polarization direction is 45°. The output polarization is always parallel to the input polarization. The light then passes through the liquid crystal layer, where the optical thickness of the liquid crystal layer is equivalent to the thickness of a quarter-wave layer QWP. The light is then reflected on a mirror and passes through the two layers in the opposite direction. Through the control of the liquid crystal layer, the optical axis of the liquid crystal is rotated in the plane. This rotation causes a phase modulation. In this case, the total phase modulation (total of the forward and return trips) is equivalent to twice this rotation angle.

Therefore, the optical axis of the liquid crystal needs to be rotated by +/-90° (+/-π/2) to achieve the phase modulation of +/-π. The advantage of this configuration is that there is no need for QWP at the rear, and the disadvantage of this configuration is that the driving voltage range may be relatively high.

Figure 31 shows a way to achieve phase modulation based on the in-plane liquid crystal mode (b), where the in-plane liquid crystal mode is like a LCoS with electrode E and dielectric mirror DE as shown in Figure 27. Figure 30 installation. The advantage of this configuration in LCoS is that there is no need to provide an additional quarter-wave plate between the liquid crystal layer and the back surface of the LCoS. The requirements for the rotation angle can be controlled within the range of +/-90°. Optically, only the in-plane phase configuration is preferable.

The configuration of the in-plane and out-of-plane mode phase modulation LCoS described so far has a feature that it does not change the incident polarization, but the light with the same linear polarization returns to the original place from the LCoS, as if the LCoS also has incident light. .

Devices that combine light beams that interact with adjacent pixels of a light modulator, especially devices that have a beam splitting or beam combination birefringent layer or other polarization sensitive elements such as the first or second patent application Combines the rays of different polarizations from two adjacent pixels. On the other hand, the liquid crystal layer itself often needs a specific incident polarization in order to modulate the phase in a desired way.

The following describes the problem of combining the phase-modulated light modulator with the device for combining the light beams interacting with the adjacent pixels of the light modulator in the first or second item of the scope of the patent application. Regarding the basic configurations (a), (b) and (c), the output polarization is always parallel to the input polarization. However, the beam combiner requires pixel groups, where pixel 2 has an output polarization perpendicular to pixel 1.

The following figures show different configurations. The purpose of using these configurations is to achieve the desired different polarizations of the reflected light in adjacent pixels. These configurations are suitable for being integrated into the device for combining light beams interacting with adjacent pixels of the light modulator as in any one of the scope of the patent application item 1 to item 17, and/or suitable for being integrated into A device having 2D and/or 3D images and/or dynamic scenes of a device for combining light beams interacting with adjacent pixels of a light modulator as in at least any one of items 1 to 17 of the scope of the patent application .

The device shown schematically in Figure 32 is to generate a different polarization for adjacent pixels for the in-plane modulated liquid crystal mode, which is option (1). The exit end of this device has a structured polarizer sP, so the incident light from different pixels can only enter the modulator with horizontal or vertical polarization. For example, 45° linearly polarized light can be used to illuminate the modulator, which means that this polarized light contains There are vertical and horizontal components. The structured polarizer sP allows the appropriate polarized portion of the incident light to pass. Then an unstructured quarter-wave layer nsQWP with a fast axis of 45° converts the incident light into circularly polarized light, but the direction of circular polarization is different for adjacent pixels. Therefore, alternating right circular and left circular polarized light will be formed for adjacent pixels.

The light then passes through a liquid crystal layer of the light modulator SLM (the optical thickness of which is equivalent to the thickness of a quarter-wave plate), and is then reflected on the mirror and passes back through the aforementioned elements. The liquid crystal molecules rotate in the plane to produce a phase modulation proportional to the double rotation angle, but the signs of the phase modulation of the left circulating light and the right circulating light are different. According to the present invention, this is taken into consideration when the phase value is written into the light modulator. For example, by turning on an appropriate voltage, a positive phase value of the liquid crystal molecules is generated in the even-numbered pixel column for the same phase value to be written. The rotation angle of, and a negative rotation angle of the liquid crystal molecules in the odd-numbered pixel column. The advantage of option (1) is that there are no structural components on the backplane (BP) side, while the disadvantage of option (1) is that QWP and sP are within the settings. It is similar to the in-plane of option (1d), where the thick layer must be structured.

Especially for small-sized pixels, the influence of the diffraction effect of light propagation between the structured polarizer and the liquid crystal layer should be minimized. Therefore, an advantageous approach is to reduce the distance between the structured polarizer and the liquid crystal layer.

Therefore, a very advantageous way is to "embed" the quarter-wave plate and the structured polarizer, that is, the quarter-wave plate and the structured polarizer are arranged on the glass substrate (not shown in Figure 32). The inner side is close to the position of the liquid crystal layer.

This kind of device with a structured polarizer on the outside is suitable for in-plane modulation of liquid crystals, because both the right circularly polarized light and the left circularly polarized light will undergo phase modulation.

In contrast, the phase modulation of the linear polarization of the out-of-plane modulated liquid crystal is only in a specific polarization direction. For example, in the ECB mode, the liquid crystal molecules in the open state are aligned (that is, for example, through the mechanical friction of the PI layer, The rubbing direction parallel to the orientation of the liquid crystal).

Therefore, an out-of-plane modulation liquid crystal device with a structured polarizer may cause only the second pixel in each group of pixels to be phase-modulated, while other pixels are not controlled by the pixels, and the phase always remains unchanged. This relationship is described below. The simplest form of the structured polarizer at the input is only suitable for the basic configuration (a) and (b), but not for the basic configuration (c). For configuration (c), only pixels with a polarization of 0 degrees have phase modulation, and pixels with a polarization of 90 degrees have no phase modulation. However, there are still other options for configuration (c), including option (1b).

Figure 33 shows a solution to this problem. The device shown in the figure is an out-of-plane modulation LC option (1b) with a structured surface alignment and a structured polarizer as shown, and a structured polarizer sP as shown in FIG. 32. Different linearly polarized light passes through the pixels of the liquid crystal layer of the light modulator SLM, wherein the optical thickness of the liquid crystal layer is preferably equivalent to the thickness of a λ/2 layer. In addition, the liquid crystal layer also has a pixel-like structured alignment of liquid crystal molecules. The alignment of the liquid crystal molecules is parallel to the passing direction of the structured polarizer Sp in front of each pixel. For example, when manufacturing a light modulator, an appropriate mask can be used to transmit light alignment to achieve such alignment. Due to the proper alignment of the liquid crystal molecules, when the out-of-plane liquid crystal molecules are modulated, phase modulation is performed in each pixel. However, such devices that require structured alignment of liquid crystals are very expensive. In addition, the disadvantage of option (1b) is that this configuration requires optical alignment (not a standard technology for LCoS) and the fringe field may become larger due to structured alignment. In contrast, the advantage of option (1b) is that no special materials are required on BP.

Therefore, another solution is proposed according to Figure 34, which is to use the out-of-plane modulation liquid crystal option (1c) with structured polarizer sP. A structured half-wave layer sHWP is provided between the structured polarizer sP and the liquid crystal layer of the light modulator SLM. The structured half-wave layer sHWP rotates the polarization by 90° for each second pixel. The effect of this is that, for all pixels, before passing through the structured polarizer sP and reaching the structured half-wave layer sHWP, differently polarized light rays pass through the structured half-wave layer sHWP and enter the liquid crystal layer. When being the same polarization. In the open state, the direction of the selected liquid crystal molecules (for example, the rubbing direction) is parallel to the incident polarization direction. Therefore, the phase modulation can be adjusted for the out-of-plane modulation of the liquid crystal layer of all pixels. After passing through the liquid crystal layer, on the return journey from the structured half-wave layer sHWP, the polarization becomes the structured polarizer sP again. In this way, it is possible to perform phase modulation with the desired different polarizations of the light emitted by the adjacent pixels from the light modulator SLM. This configuration has a standard reflective cell gap. The advantage of option (1c) is that there are no additional components on the BP, but the disadvantage is that there is a sandwich of at least two structured layers.

Another configuration (d) of Figure 35, which is option (1d), shows another possibility of phase modulation with different polarizations of light emitted from the light modulator SLM by the out-of-plane modulation liquid crystal and adjacent pixels.

This configuration requires neither a structured liquid crystal layer nor a structured polarizer. This configuration is similar to option (1c), but without a structured polarizer. Linearly polarized light is irradiated on the structured half-wave layer sHWP at an angle of 45°. The structured half-wave layer sHWP has alternating isotropic (non-birefringent material) layers and (birefringent) λ/2 layers, and 45 °Optical axis for angular alignment. On the forward path, light passes through the structured half-wave layer sHWP at an angle of 45° (without rotation), because the optical axis is parallel to the polarization direction of the incident light at 45°, and because the isotropic material does not change the optical axis. The light then hits a polarizer P with a passing direction of 0°. About 50% of the light is absorbed by the polarizer P, and the other The outer 50% of the light reaches the liquid crystal layer of the light modulator SLM with uniform polarization, where the phase polarization can be adjusted in the liquid crystal layer. On the return journey, the light passes through the polarizer P again with the unaltered polarization. The structured half-wave layer sHWP rotates the polarization by 90° only in the section where the direction of the optical axis is 45. In the passage between the structured half-wave layer sHWP containing isotropic material, the polarization will not be rotated. In this way, the light emitted by the device can be polarized differently to adjacent pixels as desired. It is best to produce this different polarization when the light passes through the last layer of the device. Contrary to the aforementioned embodiment, this embodiment only requires one structured layer, that is, the structured half-wave layer sHWP.

The disadvantage of this configuration is that the polarizer P is located between the liquid crystal layer of the light modulator SLM and the structured half-wave layer sHWP. Therefore, in order to reduce the adverse diffraction effect when light propagates between the liquid crystal layer and the structured half-wave layer sHWP, the thickness of the polarizer P must be small. Generally, thin-film polarizers with a thickness greater than 100 microns may not be applicable to small-sized pixels. Therefore, it is necessary to consider the use of special thin-layer polarizers with a thickness in the range of 5 to 10 microns.

Figure 36 shows a detailed view of the configuration of Figure 35. Some places (such as the pixel pitch) and the relative thicknesses of the liquid crystal layer, ITO, PI, structured half-wave layer sHWP, and polarizer P of the light modulator SLM are drawn in approximate proportions, which are not completely accurate. DG is much thicker than other layers.

The reflective light modulator (from left to right) has a backplane BP for control, with a reflective electrode E on the top (left), and a "black mask" BN in the space between pixels if necessary, and then on top It is a PI layer (such as polyimide) that aligns the liquid crystal of the light modulator SLM, followed by a liquid crystal layer with an optical thickness at least equivalent to a λ/2 layer (the optical thickness can also be greater than the λ/2 layer), Followed by a second alignment layer PI, behind the second alignment layer PI is a transparent electrical Extremely configured LE, such as IOT. In this example, the electrode configuration LE is an FFS type electrode LE as described in Figure 25, that is, a linear electrode, followed by an insulating layer I and a planar electrode tE. The electrode tE is connected to a polarizing layer P (thin layer polarizer) with a thickness of at least a few microns and a structured half-wave layer sHWP, where the structured half-wave layer sHWP is aligned with the pixel (birefringence, the optical axis is at 45° The angle relative to the passing direction of the polarizer alternates with the non-birefringent insulating paragraph, as described in Figure 35). The second alignment layer PI, the electrodes LE and tE, the polarizer P, and the structured half-wave layer sHWP are all located inside the glass substrate DG (not drawn to scale in the drawing).

During manufacturing, each layer on the glass substrate DG is usually formed first, and then the glass substrate DG is oriented toward the back plate surface BP, and finally the liquid crystal layer is installed. In this configuration, there are only additional layers on the glass side, the BP process is unchanged, and the DG and pixel positions need to be adjusted. It is worth noting that HAN also has a similar configuration on the glass side, as shown in Figure 37.

According to a special embodiment, the glass substrate DG can be used to superimpose the light of two pixels, and as a birefringent Sawater wave plate. For example, the glass substrate may be made of quartz glass with an appropriate alignment of the optical axis. According to another embodiment, the glass substrate DG is a common display glass on the market, and at the same time, in the optical path, an external Sawatt wave plate is provided after the light modulator.

Figure 37 shows a device similar to Figure 36, except that the device in Figure V36 is an in-plane modulation light modulator SLM with a liquid crystal layer. This is the HAN type, which is the basic in-plane configuration (b). From right to left are the glass substrate DG, the structured half-wave layer sHWP and the polarizer P in sequence. But there is also a quarter-wave layer QWP on the left side of the polarizer P, because the in-plane phase modulation of the SLM requires circularly polarized light. In this example, the right side of the liquid crystal layer does not need to be liquid Electrodes are provided in a liquid crystal mode where the in-plane electric field is modulated in-plane. Figure V36 shows a liquid crystal layer with alignment layers PI on both sides. In this case, the optical thickness of the liquid crystal layer is equivalent to the thickness of a quarter-wave layer.

As described in FIG. 27 and the text therein, the linear electrode LE with the dielectric mirror DE disposed between the electric field E can be applied to the liquid crystal mode with the in-plane electric field. These electrodes are shown on the left side of the diagram.

But there are also some liquid crystal modes that rotate in a plane with liquid crystal molecules in an adjacent out-of-plane electric field. For example, it has a smectic liquid crystal molecular liquid crystal mode, or a uniform transverse helix mode (ULH) with cholesteric liquid crystal. The same device composed of wave plates and polarizers (as shown in Figure 37) can also be applied to these liquid crystal modes, but flat electrodes should be provided on the back plate side and the glass substrate. For example, the electrode configuration is the same as in the case of Fig. 36.

Figure 38 shows another device for out-of-plane modulation in the liquid crystal layer, which is option (2). On the back of this device, a structured quarter-wave layer sQWP is arranged between the liquid crystal layer and the mirror of the light modulator SLM, and the other optical thickness arranged on the optical axis is equivalent to half of the previous figures. The optical thickness of the wave plate (the (birefringent) quarter wave layer with an optical axis of 45° is exchanged with the (non-birefringent) isotropic layer Iso).

Linearly polarized light (0°) is irradiated on the light modulator SLM and passes through the liquid crystal layer with this polarization on the forward path. Then, through the structured quarter-wave layer sQWP, the polarization is rotated by 90° for each second pixel. Since the ECB mode out-of-plane modulation liquid crystal is only used for phase modulation in one linear polarization direction, it will only be used for each second pixel (in the structured quarter-wave layer sQWP) when it passes through the liquid crystal layer for the first time. 45° structured quarter-wave layer sQWP position) produces a light Phase modulation. Therefore, the liquid crystal layer has a relatively large optical thickness, which is at least equivalent to the thickness of a full-wave plate FWP, so as to achieve a phase modulation equivalent to 2π for all pixels.

Figure 39 shows a detailed view of the same configuration. It can be seen from the diagram that from left to right are the backplane BP, the reflective pixel electrode E, the black mask BM between the pixels, the structured quarter-wave layer sQWP, and an alignment layer PI (such as poly Imide), the liquid crystal layer of the light modulator SLM, the second alignment layer PI, an ITO plane electrode tE, and the glass substrate DG. In this case, since the back of the structured quarter-wave layer sQWP is on the same substrate as the pixel electrode E, and the glass substrate DG has no structured components, there is no need to adjust the relative back to the glass substrate DG when placing the glass substrate DG. The position of the board BP. There are additional layers only on the BP side of the backplane. The disadvantage of this device is that the reaction speed of the thicker liquid crystal layer is usually slower. Organic materials can be a problem during wafer processing. It is worth noting that this configuration only works in out-of-plane mode.

Figure 40 shows another possible device, which is option (2b): On the back of the device, an unstructured quarter-wave layer nsQWP is provided between the liquid crystal layer of the light modulator SLM and the mirror. The LC layer is still a full wave plate FWP. At this time, looking at the liquid crystal layer of the light modulator SLM, the structured quarter-wave layer sQWP is on the other side. However, the cost of this device is higher than that of the device described in Figure 39.

The following diagram shows another device with a polarizer on the back side between the liquid crystal layer and the mirror.

The first to be described below is the in-plane liquid crystal mode.

The device shown in Figure 41, which is option (3), has two quarter-wave layers, nsQWP and sQWP, one of which is an unstructured wave plate and the other is a structured wave plate. Linearly polarized light is converted into circularly polarized light by the first unstructured quarter-wave layer nsQWP. This circularly polarized light is The second structured quarter-wave layer sQWP with alternating +45° and -45° optical axes is again converted into linearly polarized light with alternating 0° and 90° polarization directions. For example, in a transmissive device, a liquid crystal layer for phase modulation can be provided between two structured quarter-wave layers nsQWP and sQWP.

Therefore, it is only necessary to pass through two quarter-wave layers once to achieve the goal of obtaining different linear polarizations for each second pixel.

But for the reflective device (basic configuration (a)), the polarization rotation will return to the original state after passing through the two quarter-wave layers nsQWPs for the second time, thus forming the same polarization for all pixels.

The consideration of the device described below is that between the first pass and the second pass through the quarter-wave layer, that is, close to the side of the mirror, a polarizer is provided, which is used to reduce the 1/4-wave plate in The effect of one pass, but the effect of keeping the 1/4 wave plate in another pass.

Figure 42 shows one such device, this is option (3a). Figure V41 also shows a headlight lighting device FL (equivalent to the lighting device of WO 2010/149583 A1) that illuminates the light modulator SLM. However, the headlight lighting device FL is not an indispensable part of this embodiment. For example, it is also possible to illuminate through a polarization beam splitting cube, and another half-wave plate that rotates the polarization by 45° can be selectively installed between the beam splitting cube and the device.

The light with 45° linear polarization is irradiated on the structured quarter-wave layer sQWP with the optical axis +45° and -45° alternately aligned. Since the orientation of the structured quarter-wave layer sQWP can be selected to be perpendicular or horizontal to the polarization direction of the incident light, its polarization state is maintained at linear and 45°.

The linearly polarized light passes through the liquid crystal layer of the light modulator SLM, and then irradiates a quarter-wave layer QWP (the orientation of the optical axis is also 45°), and then propagates to a reflective polarizer rP (or propagates to a reflective polarizer rP). TP and reflector components). This polarizer is installed on the back side only for basic in-plane configuration (a), not for basic in-plane configuration (b).

Only linearly polarized light returns from the polarizer rP at 0 degrees and passes through the aforementioned layers in the reverse order, that is, through the quarter-wave layer QWP, which is cyclically polarized, and, through the LC layer, and then through the structured quarter-wave layer sQWP is linearly polarized alternately at 0 degrees or 90 degrees for adjacent pixels.

Another possible way is the structured and unstructured quarter-wave layers sQWP and nsQWP in the switching device, that is, the structured quarter-wave layer sQWP is arranged between the liquid crystal layer and the reflective polarizer rP.

However, the disadvantage of this embodiment with a reflective polarizer rP on the back is that the polarizer will cause a 50% loss of incident light.

Figure 43 shows the detailed structure of the same device. As can be seen from the figure, from right to left are a glass substrate DG, an ITO electrode located inside the glass substrate DG, a structured quarter-wave layer sQWP, and a PI layer (polyimide ), a liquid crystal layer of the light modulator SLM, another PI layer (polyimide, the optical thickness of which is equivalent to a half-wave plate) for aligning the liquid crystal, and another quarter-wave layer QWP.

The pixel electrode E for generating an in-plane electric field is arranged between the pixels on the back plate side, and a reflective polarizer (in this example, a wire grid polarizer WGP) is arranged therebetween. Since the wire grid polarizer contains metal (with conductivity), an insulating layer is provided above the wire grid polarizer and between the wire grid polarizer WGP and the electrode E. (The extra t _off electrode on the front of the glass substrate is not shown in the figure.)

Since the wire grid polarizer WGP reflects the linear polarization direction, but allows the polarization direction perpendicular to it to pass through. In this example, a black mask BM is provided behind the wire grid polarizer WGP on the back plate side, and its role is to absorb through Passing light.

Figure 44 shows a more advantageous device than Figures 42 and 43. In this device, both quarter-wave layer QWPs are unstructured. But the reflection polarization set on the backplane The polarizer is a pixel-like structure, which is called a structured reflective polarizer srP. The setup can also be equipped with a structured polarizer sP and an unstructured quarter-wave layer nsQWP.

The structured metal wire grid polarizer WGP on the backplane can also be manufactured by a semiconductor process. Since there are only structured elements on the backplane, the position of the glass substrate is not aligned with the backplane when manufacturing the SLM.

The incident light only passes through the unstructured layer on the outgoing path toward the structured reflective polarizer srP. Then on the polarizer srP, the linearly polarized light is reflected alternately at 0° and 90° in adjacent pixels. The light passes through a quarter-wave layer QWP, so it is circularly polarized, and then passes through the liquid crystal layer of the light modulator SLM and another quarter-wave layer QWP, so it alternates between 0° and 90° in adjacent pixels. It is linearly polarized and emitted from the device.

Figure 45 shows the detailed structure of the same device. As can be seen from the figure, from right to left are a glass substrate DG, an ITO electrode E located inside the glass substrate, the first quarter-wave layer QWP, and a PI layer (polyimide ), a liquid crystal layer of the light modulator SLM (its optical thickness is equivalent to a half-wave plate), another PI layer (polyimide) for aligning the liquid crystal, and another quarter-wave layer QWP. The pixel electrode E for generating an in-plane electric field is arranged between the pixels on the back plate side, and a reflective polarizer (in this example, a wire grid polarizer WGP) is arranged therebetween. The wire grid polarizer WGP is structured. For example, it can be structured through different orientations of "lines", that is, structured through the alignment of metal wires. For example, the pixels below the drawing surface are parallel to the drawing surface, and the pixels above the drawing surface are vertical.于图面。 On the drawing. Through the structure of the wire grid polarizer WGP, for each second pixel (the pixel at the top of Figure 45), the light is reflected in a linear polarization of 0°, and for the other pixels (the pixel at the bottom of Figure 45), the light is reflected It is reflected in 90° linear polarization. As already mentioned in the previous device, above the wire grid polarizer WGP and the wire grid polarization An insulating layer I is provided between the WGP and the electrode E. Similarly, a black mask BM is provided behind the backplane side wire grid polarizer WGP.

Figure 46 shows the liquid crystal mode using the back polarizer rP for out-of-plane modulation, which is option (3b). This basic setup (c) has a back polarizer. This embodiment also uses the headlight lighting device FL. The 0° linearly polarized light emitted by the headlight lighting device FL irradiates a structured 1/4 wave layer sQWP, so that the light of adjacent pixels is alternately right circularly polarized and left circularly polarized, and then the light propagates to the liquid crystal of the light modulator SLM Layer and polarizer rP. Only the linearly polarized part of the incident circularly polarized light is reflected by the polarizer rP, so there is a 50% light loss. Then linearly polarized light passes through the liquid crystal layer, and then passes through the structured quarter-wave layer sQWP again, so that the light of adjacent pixels is alternately right circularly polarized and left circularly polarized, and then passes through the headlight lighting device FL, and then passes through After passing through another unstructured quarter-wave layer nsQWP, the light of adjacent pixels is alternately linearly polarized by 0° and 90°. The disadvantage of this arrangement may be that the polarizer is not easy to manufacture. The polarizer is affected by the liquid crystal drive voltage and fringe field.

Figure 47 shows the detailed structure of the device option (3b). As can be seen from the figure, from right to left is a glass substrate DG and electrodes tE and LE located inside the glass substrate in sequence. Similar to Figure 36, the electrode tE is composed of a flat ITO layer tE, an insulating layer I, and a linear electrode junction LE. The function of the planar electrode tE is to generate an out-of-plane electric field, and the linear electrode LE can be used to quickly cut off the liquid crystal of the light modulator SLM through the in-plane electric field.

The electrodes tE and LE connect a structured quarter-wave layer sQWP, a PI layer (polyimide) that aligns the liquid crystal, a liquid crystal layer whose optical thickness is equivalent to a half-wave plate, and another PI that aligns the liquid crystal Layer (polyimide), there is a reflective polarizer rP on the back plate side. If gold For the wire grid polarizer, the polarizer and pixel electrode are the same for the out-of-plane liquid crystal mode. It is necessary to make contact with the "line" within the pixel.

Under the reflective polarizer rP, there is a black mask BM for absorbing light. The electrodes pass through the black mask BM and are electrically connected to the back plate BP.

The light modulator SLM of this embodiment is applied to a reflective beam combiner, where the light modulator SLM is based on in-plane modulation or out-of-plane modulation. The disadvantage is that the liquid crystal itself is usually only a specific polarization state (through (Through the liquid crystal layer) to produce the required phase modulation.

It is necessary to obtain the desired phase modulation after passing through the liquid crystal layer and other optical layers twice, and at the same time to obtain the linear polarization that is perpendicular to the adjacent pixels, just like the adjacent pixels used in the combination and the optical modulator. The light beams of the two pixels of the device of the pixel-interacting light beam are combined (for example, the purpose of using a Sawater wave plate), which can usually only be achieved under the condition of loss of light intensity.

Many of the embodiments presented above have a polarizer that absorbs 50% of the incident light. This loss will not only weaken the efficiency of the optical modulator, but also increase the energy consumption of the optical modulator.

Figure 48 shows a more advantageous device, which has a micro-electromechanical system (MEMS) light modulator that performs phase modulation based on displacement (that is, the mechanical adjustment of the micro-mirror HS). The phase modulation using the shifting mirror HS is independent of the incident polarization. If a structured quarter-wave layer sQWP with alternating 45°1/4-wave layer and isotropic layer is used before the microelectromechanical system (MEMS) mirror HS, the incident linearly polarized light is 0° In this case, the structured quarter-wave layer sQWP is that adjacent MEMS mirrors HS alternately generate linearly polarized light or circularly polarized light. Different from the commonly used liquid crystal mode, the MEMS mirror HS may be able to produce the same phase modulation for cyclic and linearly polarized incident light.

The light reflected by the MEMS mirror HS passes through the structured quarter-wave layer sQWP for the second time, so that the circularly polarized light is converted into linearly polarized light again, but its direction is rotated by 90° in the incident direction. The light still passes through adjacent pixels in a linear polarization of 0°, that is, the pixel to which the isotropic layer of the structured quarter-wave layer sQWP belongs. In this embodiment, there is no need to additionally provide a polarizer on the SLM, so there is no loss of light intensity.

The device in Fig. 48 has a headlight illuminating device FL that couples light and a glass substrate DG. The glass substrate DG itself is birefringent and acts like a Sawatt wave plate (beam splitter and/or beam combiner). ). For example, the structured quarter-wave layer sQWP can be disposed inside the glass substrate DG. The incident light from the headlight FL passes through the glass substrate DG without shifting, and then passes through the device composed of the quarter-wave layer sQWP and the MEMS mirror HS. On the return journey, the light passes through the glass substrate DG (Savat wave plate), and at the same time the pixel with the 90° rotation polarization on the upper side is shifted, so it is superimposed on the lower pixel.

Then the combined light of the two pixels passes through the headlight illuminating device FL and irradiates a polarizer P at an angle of 45°. The function of this polarizer P is to perform amplitude modulation according to the relative phase of the two pixels, just like a beam combiner with a Sawat wave plate.

The implementation with a micro-electromechanical system (MEMS) is not limited to the application of the glass substrate DG (also serving as a Sawatt wave plate), nor is it limited to the application of the headlight lighting device FL.

Compared with the SLM based on the liquid crystal mode, the important feature of the device with MEMS is that the structure of the SLM with the structured quarter-wave layer sQWP (alternating 45° optical axis, isotropic) is relatively simple.

The application range of the device in Figure 48 is not limited to MEMS light modulators, but can also be applied to all other types of light modulators, provided that it can be phase modulated with incident light. The polarization is irrelevant. This includes special liquid crystal modes, such as a blue phase mode with an out-of-plane adjacent electric field.

Figure 21 of DE 10 2009 044 910 A1 shows an example of a beam combining device. This beam combining device is not composed of a single optical birefringent uniaxial member, but is composed of two optical birefringent uniaxial members and located between the two optical birefringent uniaxial members. It is composed of half-wave plates between two components.

The reflective device described here can also optionally be equipped with such a beam combining device, that is, a beam combining device composed of a plurality of optical birefringent components.

Fig. 49 shows a device with a MEMS light modulator and a headlight illuminator FL as shown in Fig. 48. This beam combiner is composed of two birefringent uniaxial members Sp1, Sp2 and a half-wave layer HWP45 located between the two uniaxial members, in which the optical axis (crystal axis) of the two uniaxial members rotate 180 with each other °, the optical axis of the half-wave layer HWP45 has an angle of 45° with respect to the polarization of the incident light.

The half-wave plate HWP45 rotates the polarization of the incident light and the output light by 90°, so the incident light and the output light pass through a birefringent uniaxial member Sp1 as an ordinary beam and another birefringent uniaxial as an extraordinary beam. Component Sp2.

Reflective light modulators usually have smaller pixels, and the pixel pitch is less than 10 microns. Therefore, even if an asymmetric beam combiner is used, its flip tolerance is greater than that of transmissive light modulators with larger pixels. As shown in Figure 49, an advantage of a device equipped with a beam combiner composed of a plurality of optical birefringent uniaxial members Sp1 and Sp2 is that it can expand the tolerance for flipping.

The application of the beam combiner composed of a plurality of optical birefringent uniaxial members Sp1, Sp2 is not limited to the implementation with MEMS light modulators, but can also be applied to the implementation of the light modulation device in Figures V30 to V46 Way.

Several implementations of light modulation devices are proposed below. These implementations are all suitable for modulating the light guided by the reflected beam in space, and compared with the prior art light modulation devices, the switching time of these light modulation devices is longer. Short, and/or these light modulation devices have a device for combining light beams interacting with adjacent pixels of the light modulation device as in any one of items 1 to 17 in the scope of the patent application, especially for light irradiation The sensitivity of the incident angle change on the beam combination device as shown in Figs. 10-20 becomes smaller. A particularly advantageous approach is to integrate this light modulation device into a 2D and/or 3D image and/or dynamic scene device, especially into at least any one of items 1 to 17 of the scope of patent application. In the device.

1. A light modulation device used for reflective light beam guidance, having a spatial light modulator, the spatial light modulator having a plurality of pixels and a back plate for electrically controlling the pixels, and having at least one light beam influencing element, Its function is to produce a pixel-like effect on the light interacting with the pixels of the light modulator, and/or has at least one electrode device, and its function is to accelerate the alignment of the liquid crystal during the on process and/or the off process.

2. The light modulation device according to the first embodiment, wherein the pixels of the light modulator contain liquid crystals, and due to the control orientation change, these liquid crystals will change the phase (optical path) of the light interacting with the pixels.

3. The light modulation device as in the second embodiment, in which the liquid crystal is arranged so that it can realize "in-plane" modulation by controlling the orientation change, especially the IPS mode, HAN mode, CIPR mode, or the liquid crystal in the plane in the electric field Smectic liquid crystal mode that rotates far more than out-of-plane rotation, or cholesterol phase mode, this kind of optical axis has an in-plane rotation mode in the electric field (uniform lateral spiral mode, abbreviated as ULH).

4. The light modulation device as in the second embodiment, in which the liquid crystal is arranged so that it can realize "out-of-plane" modulation by controlling the orientation change, especially in the ECB mode.

5. The light modulation device of the third or fourth embodiment, wherein a structured electrode device is provided between the backplane and the light modulator, and the electrode is located in the area between adjacent pixels, and/or each A pixel-especially a flat pixel-has an electrode.

6. The light modulation device according to the fifth embodiment, wherein at least one insulating layer is provided therein, and its function is to insulate the structured electrode device from other conductive elements of the light modulation device.

7. The light modulation device as in any one of the second to sixth embodiments, wherein an electrode device and/or a structured electrode device is provided on the side of the back plate facing away from the light modulator.

8. The light modulation device according to the fourth embodiment, wherein the beam influencing element has at least one structured polarization influencing device arranged between the backplane and the light modulator, and its structure and configuration are such that it can affect adjacent pixels. The light causes different polarization effects.

9. The light modulation device of the 4th or 8th embodiment, wherein the beam influencing element has at least one structured polarization influencing device, wherein the at least one structured polarization influencing device is arranged on the back plate and facing the light modulator That surface, and its structure and configuration make it possible to cause different polarization effects on the light of adjacent pixels, and can form a structured quarter wave plate, structured half wave plate, or structured wire grid polarization Device.

9. The light modulation device according to the fourth, eighth, or ninth embodiment, wherein the beam influencing element has at least one structured polarization influencing device or polarizer, wherein the at least one structured polarization influencing device or polarizer Is set between the backplane and the light modulator, and/or set It is placed on the side of the backplane facing away from the light modulator, and can form a structured quarter-wave plate, structured half-wave plate, or structured wire grid polarizer.

10. The light modulation device according to any one of the first to ninth embodiments, wherein the light modulator or a reflective element is structured and controlled so that it can cause different polarization effects on the light interacting with adjacent pixels .

11. The optical modulation device according to any one of the first to tenth embodiments, wherein the optical thickness of the optical modulator is substantially equivalent to the optical thickness of a half-wave plate or a quarter-wave plate.

12. The light modulation device according to any one of the first to eleventh embodiments, wherein the light-modulated pixels have different pixel structure or linear structure characteristics.

13. The light modulation device according to any one of the first to 12th embodiments, wherein the light modulation device is illuminated by light, and the light is deflected or guided toward the light by the headlight illuminator or the neutral beam splitter The direction of the modulation device.

PS: Polarization selective layer

WP: Delay wave plate

Pol: Polarizer

Claims (20)

A device for combining light beams interacting with adjacent pixels of a light modulator, wherein the light modulator has a plurality of pixels, and each two adjacent pixels form a giant pixel, and for one giant pixel, the beam splits The structure and design of the device make it split the incident light beam into a first partial light beam and a second partial light beam. Directional propagation, where a first structured beam influencing element is arranged between the beam splitter and the light modulator. Its function is to enable the first part of the beam to be affected in a different way than the second part of the beam. After the pixels interact, the first part of the beam and the second part of the beam pass through the second structured beam influencing element, whose function is to make the first part of the beam be affected in a different way from the second part of the beam. A beam combiner is provided in it. The function is to combine the first partial beam and the second partial beam. A beam selector is provided between the light modulator and the first or second structured beam influencing element. Part of the light beam and/or the second part of the light beam. A device for combining light beams interacting with adjacent pixels of a light modulator, wherein the light modulator has a plurality of pixels, and each two adjacent pixels form a giant pixel, and for one giant pixel, the beam splits The structure and design of the device make it split the incident light beam into a first partial light beam and a second partial light beam. Directional propagation, in which a structured beam influencing element is arranged between the beam splitter and the light modulator. Its function is to enable the first part of the beam to be affected in a different way from the second part of the beam. A reflective medium is provided in it. The function is to reflect part of the light beam, where after interacting with the pixels of the light modulator, the first part of the light beam and/or the second part of the light beam pass through the structured beam influencing element and pass through the beam splitter again, In order to combine the first part of the beam and the second part of the beam again, a beam selector is provided between the light modulator and the structured beam influencing element, and its function is to select the first part of the beam and/or that does not belong to the giant pixel The second part of the beam. For example, the device of the first item of the scope of patent application, wherein the beam splitter and the beam combiner are identical birefringent uniaxial optical components, and/or made of the same material, and/or have the same optical axis, wherein The alignment of the optical axes of the two birefringent uniaxial optical components is set so that the angle (θ) between the two components and the interface is the same as the angle between the ordinary and extraordinary partial beams. Such as the device of the second item of the scope of patent application, in which the beam splitter is a birefringent uniaxial optical component. For example, in the device of item 1 of the scope of patent application, at least one of the beam splitter and/or beam combiner is a volume grating, or at least one is a polarization grating. For example, in the device of item 2 of the scope of patent application, at least one of the beam splitter and/or beam combiner is a volume grating, or at least one is a polarization grating. Such as the device of the first item in the scope of patent application, in which the structured beam influencing element has a spatial structure, which can realize the function of a retarder regionally, wherein the retarder has a λ/2 wave plate and/or λ/4 wave The sheet, and/or the structured beam influencing element has a spatial structure that does not cause regional changes to the optical characteristics of the partial beam, and/or the spatial structure of the structured beam influencing element and the spatial structure of the pixel of the light modulator Cooperate. For example, the device of the second item of the scope of patent application, in which the structured beam influencing element has a spatial structure, which can realize the function of a retarder regionally, wherein the retarder has a λ/2 wave plate and/or λ/4 wave Sheet, and/or structured beam influencing element has a The optical properties of the light beam cause regionally changed spatial structuring, and/or the spatial structuring of the structured light beam influencing elements matches the spatial structure of the pixels of the light modulator. For example, in the device of item 2 of the scope of patent application, the pixels of the light modulator can reflect by themselves, or a reflecting mirror is arranged behind the light-transmitting pixels of the light modulator. For example, the device of the first item of the scope of patent application, in which the beam splitter, beam combiner, and/or the first and/or second structured beam influencing elements are designed and arranged in such a way that the optical path of the first part of the beam and the second The optical path of the partial light beam is basically symmetrical with respect to the midpoint between the first pixel and the second pixel of the giant pixel. For example, the device in the scope of patent application 2, in which the beam splitter and/or structured beam influencing element are designed and arranged in such a way that the optical path of the first partial beam and the optical path of the second partial beam are basically at the beam splitting point And/or the beam combination point is quasi-point symmetrical. Such as the device of any one of items 1 to 11 in the scope of the patent application, wherein the beam selector has a polarizer. Such as the device of any one of items 1 to 11 in the scope of the patent application, in which a beam superimposing element is provided to interfere with the first part of the light beam and the second part of the light beam. Such as the device of any one of items 1 to 11 in the scope of patent application, wherein the pixels of the giant pixels are controlled by voltages with the same sign. Such as the device of any one of items 1 to 11 in the scope of the patent application, wherein the beam splitter, the beam combiner if necessary, at least one structured beam influencing element, and/or the beam selector are close to each other Together, or fixed to each other, for example with adhesive. For example, the device of any one of items 1 to 11 of the scope of patent application, wherein the incident light beam has a linear polarization or a circular polarization, and after alignment or adjustment, the light beam can be split into a first partial beam and a second partial beam, Then combine them together. For example, the device of item 2 or item 13 of the scope of patent application, in which a flat illuminating device is provided between the light modulator and the beam splitter, or between the beam splitter and the beam superimposing element, wherein the illumination The device has a flat light conductor and an output unit, wherein the light emitted by the light conductor is output through the output unit and can be deflected to the direction of the light modulator, and the light reflected on the reflective medium is basically not deflected The way through the lighting device, and then spread out through the beam combiner. For example, the device of any one of items 1 to 11 of the scope of patent application, wherein the light modulator contains liquid crystal, and the liquid crystal is rotated out of plane, wherein the incident light beam is linearly polarized, and the structured light beam influences the regional characteristics of the element The function of λ/2 wave plate. For example, the device of any one of items 1 to 11 in the scope of the patent application, wherein the light modulator contains liquid crystal, and the liquid crystal is rotated in a plane, wherein the incident light beam is linearly polarized, and the structured light beam affects the regional characteristics of the element The function of λ/4 wave plate. A device for displaying image content has at least one device as in any one of items 1 to 11 of the scope of the patent application.

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